The chamber was packed. Young men in evening dress squeezed ten-to-a-row on the benches; more stood around the edges of the room, bodies pressed together. The lamp-lit air hung heavy with sweat and alcohol and excitement, like a prize fight at a county fair.

But no blood would be spilled tonight. This was the Cambridge Union Society: the oldest debating club in the country and the proving ground for the nation’s future rulers. The only sparring would be verbal, the only wounds to pride. At least, those were the rules.

The front of the room was set up like a miniature Parliament. The two sides faced each other from opposing benches, divided by the length of two swords. A young man named Fairchild, with sandy hair and fine features, was addressing the audience from the despatch box.

‘The motion before you tonight is, “This house believes that slavery should be abolished from the face of the Earth”. And, indeed, the case is so self-evident I feel I hardly need to argue it.’

Nods of agreement; he was preaching to the converted. Abolitionist sentiment ran high among the Cambridge undergraduates.

 ‘I know in this House we are used to debating the fine points of law and politics. But this is not academic. The question of slavery speaks to a higher law. To keep innocent men and women in chains, to tear them from their homes and work them to death: this is a crime against God and all the laws of justice.’

On the facing bench, most of the opposition speakers listened to his oration glumly. They knew they were on to a losing cause. One leaned forward and twisted his handkerchief through his hands. One stared at the speaker with such melancholy he looked as if he might burst into tears. Only the third seemed untroubled. He lounged back nonchalantly, his mouth set in a lazy smile, as if he alone was privy to some enormous joke.

‘If you have one ounce of humanity in you, I urge you to support the motion.’ Fairchild sat down to sustained applause. The President waited for the noise to die away.

‘To close for the opposition, the Chair calls on Mr Mungo St John.’

The man who had been lounging on the front bench rose. No one applauded, but a new force seemed to charge the room. Up in the gallery, where a few well-bred young ladies were allowed to observe proceedings as long as they stayed silent, crinolines rustled and stays creaked as they leaned forward to see better.

You could not ignore him. He was twenty, but he loomed half a head taller than any other man in the chamber. His dark hair flowed over his collar in a long, thick mane; his darkly-tanned skin shone with a lustre that no wan English sun could have produced. His suit was cut to accentuate his figure: a slim waist that rose to broad, well-muscled shoulders more like a boxer’s than a Cambridge undergraduate’s.

If he felt the hostility aimed at him, it did not shake the easy grin from his face. Indeed, he seemed to feed off the crowd’s energy.

‘You have heard a great deal this evening about the supposed evils of slavery. But has anyone here ever been to the great tobacco plantations of Virginia, or the cotton fields of the Mississippi?

His smoky yellow eyes surveyed the room.

‘That is my native soil. I was born and raised in Virginia. Slavery to me is not sensational reports in the newspapers, or hell-raising sermons. I have seen the reality of it.

He lowered his voice. ‘Is the work hard? Yes. Do rich men profit from the labour of others? Again, yes. But do not be gulled by these fantasies of brutality and violence you are peddled. At Windemere – my home, on the banks of the James river – my father keeps four hundred workers, and he cares for each one like his own child. When they work well, he praises them. When they are sick, he tends them. If they die, he grieves.’

‘That is because each one is worth a thousand dollars to him,’ said Fairchild. The audience laughed.

‘My friend is quite right,’ said Mungo. ‘But think of something you own that is worth that much. A fine horse, say, or a necklace. Do you beat it and disdain it and leave it in the mud? Or do you take superlative care for it, polish it and watch out for it, because it is so valuable to you?’

He leaned on the despatch box, as comfortable as if he were leaning on the mantelpiece of his drawing room enjoying a cigar.

‘I am a guest in your country. But sometimes, it takes a stranger’s eye to observe what the natives do not see. Go to Manchester, or Birmingham or any of your other great manufacturing cities. Visit the factories. You will see men and women labouring there twelve, fourteen, even eighteen hours a day, in conditions that would make my father sick to his stomach.’

‘At least they are free – and paid,’ said Fairchild.

‘And what use is freedom, if it is only the freedom to live in a slum until you are worked to death? What use is a wage if it does not buy you enough to eat? The only thing that money buys is ease for the consciences of the mill owners. Whereas at Windemere, every one of our people enjoys three square meals a day, a roof over his head and clean clothes to wear. He never has to worry if he will eat, or who will take care of his family. I promise you, if any English loom worker or coal miner glimpsed life on the plantation, he would swap his life for that in a second.’

On the opposite bench, Fairchild had risen. ‘A point of order?’

Mungo gave a languid wave to allow it.

‘Even if we accept this preposterous picture of African slaves holidaying in some benevolent paradise, the gentleman is rather coy about how those persons came to his country. Will he admit that the slave trade is nothing but a trade in suffering? Or will he try to convince us that millions of Africans willingly took a pleasure cruise to America to enjoy the benefits of the climate?’

That drew a laugh. Mungo smiled broadly, enjoying the joke with everyone else.

‘The slave trade has been illegal in Britain and America for over thirty years,’ he said. ‘Whatever our fathers and grandfathers may have done, it is finished now.’

Fairchild’s face flushed. He tried to calm his emotions – gentlemanly behaviour in these debates was prized just as much as sound arguments – but he could not hold them in check.

‘You know perfectly well that despite our government’s strenuous efforts, traders continue to flout the law by smuggling blacks out of Africa under the very noses of the Royal Navy.’

‘Then I suggest you take up your complaint with the Royal Navy,’

‘I shall,’ said Fairchild. ‘Indeed, I may inform the House that as soon as I have completed my degree I shall accept a commission in the Preventive Squadron of Her Majesty’s Navy, intercepting slavers off the coast of Africa.  I will report back from there as to the accuracy of Mr St John’s picture of the delights of slavery.

There were cheers and approving applause. Up on the ladies’ balcony, more than one corset strained with admiration of Fairchild’s manly virtue.

‘If you are going to Africa, you can report back how these negroes live in their own country,’ Mungo shot back. ‘Hungry, filthy, ignorant: a war of all against all. And then you can go to America, and say if they are not better off there after all.’

He turned to the room. ‘My virtuous opponents would have you think that slavery is a unique evil, a moral abomination unparalleled in the annals of civilisation. I urge you to see otherwise. It is merely a name for what men practice wherever they are, whether in Virginia or Guinea or Manchester. The power of the strong and wealthy over the weak and poor.’

Fairchild had started to object again. Mungo ignored him. ‘That may be an awkward truth. But I say to you, I would rather live my life a slave on a plantation like Windemere, than a so-called free man in a Lancashire cotton mill. They are the true slaves.’

He looked around the tight-packed chamber. Only the briefest glance, yet every person in the room felt that his gaze had settled directly on them. On the ladies’ balcony, the fans fluttered faster than ever.

‘Perhaps what I say offends your moral sensibilities. I will not apologise for that. Instead, I beg you to look beyond your distaste and examine the proposition with clear-eyed honesty. If you sweeten your tea with sugar from the West Indies, or smoke Virginia tobacco then you support slavery. If your father owns a mill where they spin Alabama cotton; or a bank that underwrites the voyages of Liverpool ship owners, then I say again you support slavery.’

He shrugged. ‘I do not judge you. I do not lay claim to any superior moral virtue. But the one sin of which I am wholly innocent is this: I will not play the hypocrite and weep false tears for the choices I have made. If you agree with me, I urge you to support the motion.’

He sat down. For a moment, silence gripped the room. Then, slowly, a wave of applause began from the back and swelled until it echoed around the chamber. The undergraduates might not agree with his politics, but they could appreciate a bravura performance.

Though not all of them. As the applause rose, so too did an answering barrage of boos and catcalls. Yells of ‘murderer’ and ‘blood on your hands’ were heard.

Mungo sat back, revelling in the discord.

‘Order,’ shouted the President. ‘The House will divide.’

The audience filed through two doors, one for ‘aye’ on the right, and one for ‘no’ on the left. The queue for the ‘ayes’ was noticeably longer, but a surprising number turned the other way. Mungo watched the count from his seat, the grin on his face never wavering.

The President announced the result. ‘Ayes to the right, two hundred and seven. Noes to the left, one hundred and eighteen.’

Mungo nodded, accepting the result with perfect equanimity. He shook hands with his team-mates, then took two glasses of wine and crossed the room to where Fairchild was talking with his friends. He pressed a drink into Fairchild’s hand.

‘Congratulations,’ said Mungo. ‘You spoke with great conviction.’

Fairchild took the glass reluctantly. By convention, the society’s debates were about rhetorical skill and argument: winning or losing was less important than behaving like gentlemen afterwards. But Fairchild could not hide his disdain for Mungo.

‘You take your loss in good part,’ he conceded.

‘That is because I did not lose,’ Mungo answered, in the soft drawl of his native Virginia.

‘You heard the result. I carried the motion by almost two to one. You lost.’

‘Not at all,’ said Mungo. ‘I wagered ten guineas that I could get at least a hundred votes against the motion. Nobody else thought I would get more than fifty. And though the glory of victory is very fine, I would rather have the extra gold in my purse.’

Fairchild stared. All he could think to say was, ‘I should have thought you had already made enough money out of slavery.’

 ‘Not at all. My father has vowed that when he dies, he will free all his slaves. The will is already written. I will have to find some other way of making my fortune.’ Mungo clapped Fairchild on the shoulder. ‘So you see, I will never make a penny out of that institution you revile so much. Whereas you’ – he grinned – ‘will depend entirely on the slave trade to make your living.’

Fairchild almost choked on his wine. ‘How dare you–?’

‘You are joining the Preventive Squadron, are you not? You will be paid to capture slave ships.’

‘Yes.’

‘And that is a very fine and noble profession,’ Mungo agreed. ‘But if you ever actually succeeded in exterminating the slave trade, you would be out of a job. So it is in your interest to see that slavery endures.’

Fairchild stared at him in horror. ‘Arguing with you is like arguing with the Devil himself,’ he complained. ‘White is black, and black is white.’

‘I should have thought you of all men would agree that black and white are created equal. They–’

Mungo broke off. The room was still full with undergraduates milling about, talking and drinking and carrying on the argument. But a young man was barging his way through the crowd, upsetting drinks and knocking people out of his way.

As he reached the front, Mungo recognised him. It was Sidney Manners, a stocky young man who had only got his place at Cambridge because his father owned half of Lincolnshire. With his thick neck, squat shoulders and heavy breathing, he looked like nothing more than a prize bull.

‘I have been looking for you,’ he said to Mungo.

‘I hope it did not tax your energies. I was not hard to find.’

‘You have offered the most grievous insult to my sister.’

‘Insult?’ Mungo smiled. ‘You are misinformed. I offered her nothing but compliments.’

‘You seduced her!’

Mungo made a dismissive gesture. ‘Where I come from, gentlemen do not discuss such matters.’

‘Then why have I heard of it from five different people?’ Manners took a step closer. ‘They say you had her in the organ loft of Trinity chapel, while the choir were rehearsing.’

‘That is not true. It was during evensong.’

Manners’s eyes bulged. ‘You do not deny it?’

‘I deny that I made her do anything against her will. Indeed, I could hardly have resisted her advances if I had tried.’

Mungo carefully put down his drink, then gave a conspiratorial wink. ‘I may say, your sister is a perfectly devout young woman. Always on her knees in chapel.’

Manners’ face had gone a deep shade of puce. His collar seemed to have shrunk around his neck. He struggled to breathe; his mouth flapped open, but no words emerged.

Eventually, his anger burst out the only way it could. He drew back his arm and swung a fist wildly at Mungo’s jaw.

His size gave him power, but he had no training. Mungo boxed every week, taking lessons with a former champion of England who had retired to Cambridge. He dodged Manners’ blow easily; grabbed his arm, then swept his feet from under him and dumped him on his backside

Manners jerked on the ground. Mungo looked down at him and for a second, his eyes flashed with an anger so fierce, anyone who saw it would have feared for Manners’ life. In that moment, you could not doubt that Mungo was capable of anything.

Then the anger faded, as sudden as a summer squall. Mungo’s smile returned. He nodded to the circle of spectators around him. They edged back, though they could not look away: captivated by the spectacle, yet frightened of Mungo’s power.

‘If you will excuse me, gentlemen.’

The crowded room emptied in front of him as he made his way to the door. He heard Manners staggering to his feet behind him, but he did not look back. Outside, he put on his hat and strode back towards his college. The summer night was warm, but not as warm as it would be at home in Virginia. Windemere would be turning green now, as the young tobacco plants were transplanted from their winter seedbeds out into the fields.

He had enjoyed his time in Cambridge. He had learned everything he could, made some influential friends who might serve him well later in life, and met more than a few young ladies like Clarissa Manners who were eager to share their charms with him. But he would be glad to be home.      

The moon was rising behind the tower of Great St Mary’s Church as he turned into Trinity Street. It was past curfew. The gates of his college would be locked, but that did not trouble him. He had an understanding with Chapman, the porter.

‘St John!’

An angry voice hailed him from the end of the street. Mungo kept walking.

‘St John! Stop, if you are not a coward.’

Mungo paused. Slowly, he turned back. ‘No one has ever accused me of cowardice.’

Manners stood there, silhouetted against the street lamp. He was not alone. Two of his friends flanked him, sturdy young men with ham fists and broad shoulders. One of them carried a poker, and the other a wine bottle which he gripped by the neck.

‘If you were a gentleman, I would challenge you to a duel,’ sneered Manners.

‘If you were a gentleman, I would gladly accept. But as that is clearly not the case, I will bid you goodnight.’

Mungo tipped his hat and turned away – as if completely oblivious to the armed men behind him. Manners stared after him for a moment, stupefied by his opponent’s insouciance. Then anger took over. Snarling like a dog, he charged.

Mungo heard the footsteps on the cobbles behind him. As Manners closed on him, Mungo pivoted on the balls of his feet and delivered a perfectly aimed uppercut to Manners’ chin. Manners stopped dead, howling in pain. Mungo followed up with three quick jabs to the ribs that sent Manners reeling away, clutching his abdomen.

As Manners retreated his friends moved in. They circled around Mungo, with the shambling gait of men who have been drinking. Mungo watched them carefully, calculating the effect the alcohol would have. It might make them slower – but also more unpredictable.

They waited, calling encouragement to each other. None of them wanted to suffer the same fate as Manners, but they did not want to look weak. At last the one with the poker stepped forward.

‘I will give you a lesson, you American bastard.’

He swung the poker at Mungo. Mungo took the blow on his shoulder, moving away so that he barely felt it. As he did, he grabbed the poker with both hands and tugged it forward, pulling his opponent off balance. Mungo thrust the poker back so that it hit him in the stomach, then twisted it out of his hands and cracked him over the shoulders. The man stumbled back.

Now Mungo was armed he liked his odds better. He swung around, brandishing the poker. Manners’ friends edged backwards. They were not so devoted to Manners that they wanted their heads cracked for him.

‘Are you afraid of this Yankee upstart?’ Manners had stood up. He snatched the bottle that his friend carried and broke it on the cobbles so that he was left with a jagged and glittering stump. He advanced again, more cautiously, this time. Two encounters with Mungo had taught him that much, at least.

‘I would not do that,’ Mungo said.

If Manners had been sober, he might have heard the lethal warning in Mungo’s voice. But he was drunk, and angry, and he had been humiliated. He jabbed the bottle at Mungo, swiping the broken glass towards his face.

Mungo avoided it easily. As Manners brought the bottle back, Mungo whipped the poker through the air and cracked it against Manners’ wrist. The bone snapped; the bottle flew out of his hand and smashed against a wall.

Manners howled and dropped to his knees. His two friends took one look at Mungo, the poker raised like the sword of an avenging angel, and fled. Manners was left alone with Mungo.

Mungo could have walked away. He had done so once already that evening. But Manners had tried to kill him, however incompetently, and that had unlocked a rage he had rarely felt before. He stood over Manners like an executioner, the poker raised. Strength coursed through his arms. He was not minded to be merciful. At that moment, all that existed was his rage. He would break open Manners’ head like an egg.

But as he moved to strike, a firm hand gripped the poker and stayed the blow. Mungo spun around to see Fairchild’s earnest face, teeth gritted with the effort of holding back Mungo’s arm.

‘What are you doing?’ Mungo hissed. ‘Do you think you can save this loathsome rat?’

Fairchild’s grip did not loosen. ‘I am not saving him. I am saving you. From yourself.’

‘I do not need saving.’

‘If you kill him, you will be hanged for murder.’ Fairchild prodded Manners with the toe of his shoe. ‘Is he worth that?’

The two young men stared at each other, both holding the poker. Mungo knew that what Fairchild said was true, but he could not bring himself to let go. He tried to twist the weapon from Fairchild’s grasp, heaving with all his might. Fairchild’s fingers flexed; he was not as strong as Mungo. His grip threatened to break. But he had an iron will and would not yield.

They might have stayed locked in that position all night, but at that moment footsteps sounded on the street. A sturdy man in a long dark coat emerged from the porter’s lodge and came straight towards them.

‘Mister St John, sir?’

It was Chapman, the college porter. If he was surprised to see Mungo with a poker raised like a weapon, Fairchild wrestling him for it and Manners kneeling helpless at his feet, he made no comment. Chapman had known Mungo since he arrived three years ago, and nothing the undergraduate did could surprise him.

‘A letter arrived for you, sir. It was marked “urgent”.’

Mungo blinked. The poker dropped to the ground. Manners took advantage of his reprieve to scuttle away, whimpering and clutching his wrist. Mungo wiped his hands with his handkerchief, and adjusted his cuffs and his cravat. Only then did he take the letter. It was franked from Norfolk, Virginia, dated six weeks earlier. The address was written in a clear large script, careful letters formed by a hand that was not used to writing.

Mungo showed no emotion as he slit it open and read the contents.

‘What is it?’ Fairchild asked.

Mungo ignored him. ‘Have the servants pack my trunk,’ he said to the porter. ‘I must return to Virginia at once.’