The highwayman waited in a copse near the Fighting Cocks tavern alternately stroking his horse's neck and fondling the butt of his horse pistol.

He consulted his pocket-watch; three minutes to midnight, three minutes before the stagecoach was due.

The August night was warm but frosted with moonlight, like a rich red wine that has been mistakenly chilled. Leaves rustled above him and in the distance he could see the gleam of the new railway. Even farther away, in the direction of Stockton, there was a glow in the sky from the lamps of the navvies working on the last embankments.

The highwayman talked to his horse. "Not much longer now." The horse pawed the ground impatiently.

The highwayman wore a cloak despite the mild night, a tall hat with a contemptuous brim, and a mask which exaggerated the glitter of his eyes.

Two minutes to go. The rumble of an explosion reached him from the railway workings: the navvies blasting rock, angering the landowners – and their labourers who had been told that the new steam locomotives would make their wives miscarry and their cows run dry. But tomorrow it was the navvies who would be dry because the highwayman was about to steal their wage packets, their beer money.

As the explosion died the highwayman heard the thud of horses' hooves. He consulted his watch again. One minute to midnight. He nodded approvingly because punctuality was the principal accomplice of the criminal. According to his information, which was always good, the driver would be armed with two pistols, his mate with a blunderbuss, a fair defence against the usual highway robbery but not against this one.

An owl hooted and the stagecoach appeared to the highwayman's left, the horses under the whip, as if the driver sensed predators, which wasn't surprising with the gallows down the road where, five years earlier, they had hanged a highwayman.

The highwayman gripped the horse with his thighs and cocked his long-barrelled pistol.

Two hundred yards away his accomplice made his move. He galloped towards the coach, cloak flying, pistol raised, a dark muscle of speed in the silver light.

The highwayman heard the crack of the whip across the coach-horses' backs and the shouts of the driver and his mate. He noticed the shocked faces of the coach's occupants and saw the blunderbuss raised. The explosion filled the countryside with daylight, the spent shot sounding like a summer shower. The highwayman smiled, a rare phenomenon.

His accomplice faltered. The driver took aim with his pistol and fired. The ball clattered into the copse. The accomplice swerved away from the coach and galloped off towards the railway.

The coach slowed down and stopped. The highwayman heard the murmur of voices and laughter hysterical with relief. He whispered to his horse and they trotted towards the quarry waiting for them in the moonlight.

* * *

The driver and his mate were standing at the open door of the coach, heady with victory, accepting congratulations, anticipating their reward.

The highwayman spurred his horse and shouted: "Don't move."

For a moment all movement was frozen. Then the driver went for his second pistol. A brave man, thought the highwayman, and a dead one. The bullet hit the driver in the chest, throwing him against the side of the coach. He slid into a sitting position, blood spilling over his clothes.

"And that goes for you, culley," the highwayman said to the driver's mate. "One move from you and you'll be joining your partner." He dismounted and searched him for weapons. Nothing. "Who have you got inside?"

"Three men and a lady." His voice was flaky with fear.

The highwayman peered into the coach without much interest because lifting wallets and watches and jewellery wasn't his style. "Just a friendly warning," he told them. "Don't try anything or I'll blow your heads off."

He turned to the driver's mate. "Where's the swag?"

"What swag?"

The highwayman prodded him with the barrel of the pistol. "Get it." He pointed inside the coach. "I presume two of these gentlemen are puffing Billies from the Stockton and Darlington?"

The driver's mate nodded, his voice a prisoner.

"In charge of the blunt?"

A single word escaped. "Aye."

"Then get it, culley."

The driver's mate climbed up to his seat. The highwayman guessed he was contemplating the other guns under the seat beside the leather bag filled with bank notes and gold sovereigns. "Don't," he advised him, because one killing was enough for a very ordinary job. "Just throw the bag down."

The bag fell heavily, chinking with wealth. The highwayman turned to the pale faces suspended inside the coach. "And now, Billy boys, you'll have to move quickly because the navvies are planning to go on the randy this weekend and if they don't get their wages God help the S and D. God help everyone within ten miles of it," he added reflectively. He peered at the two railwaymen, seeing middle-class comfort which was something he despised more than aristocratic idleness. Hatred sharpened his voice. "And God help you two gentlemen if the navvies ever suspect you lifted their blunt."

He walked back to his horse, limping slightly, remounted, fired the remaining barrel of his pistol at the incurious stars and galloped away. The shot made the horses move and, as the coach inched forward, the body of the driver fell back on the roadside.

A mile down the road the highwayman reined his horse to check the contents of the bag. Two thousand pounds including the money to pay contractors and engineers. A fair enough purse. But highway robbery for a criminal of his calibre? The highwayman shrugged, consoling himself with the knowledge that soon it would be his privilege to carry out the world's first train robbery.

He took his payment of £100 in notes from the bag; and, because there had been a killing, helped himself to a £50 bonus. Then he strapped the bag to the saddle and turned the horse's head towards Darlington, galloping past the gallows at great speed.

* * *

Three weeks later in an inn called The Naked Man, twenty miles from the scene of the highway robbery, a man dressed with care and amusement.

He took off a grey, swallow-tail coat, royal blue waistcoat and breeches made by Weston, the Old Bond Street tailor who had dressed Beau Brummel, and soft leather boots by Hoby, the Duke of Wellington's bootmaker. He folded the clothes carefully, put them in a trunk, and stood for a moment in the middle of the low-beamed room, naked and not unlike the figure in the inn sign. His body was powerful although the skin was delicate in places with scar tissue. He had the thighs of a horseman, the shoulders of a sedan-chair carrier and the face of a poetical prizefighter.

He put away his guns with his discarded clothes. A Manton pocket pistol, a Perry conversion of a 1790 flintlock and a couple of duelling pistols by Outridge snug in their baize-lined case beside powder flask, bullet mould, balls, cleaning rod and turn-screw. He was left with a battered flintlock with rust on the barrel which he handled with distaste. When he cocked it the sound was like an old man kneeling.

Then he began to dress: moleskin trousers, double-canvas shirt, velveteen coat, hobnail boots, sealskin cap which had cost him £15s more than it was worth – red silk handkerchief with white spots round his neck and a waistcoat which embraced most of the spectrum.

He examined himself in a long, tarnished mirror which made no contribution to narcissism, and grinned. He took off the rainbow waistcoat and the sealskin cap because they were for special occasions such as pay-day brawls.

Then he went down the drunken stairs, winked at the landlord whom he had bribed to keep quiet and walked out into the purring summer day to buy the rest of his gear – a bag, a shovel and a dog.

He got the bag for 3d, the shovel for 2s, and the dog for 1d, which was more than it was worth. It had a ratty face, reddish eyes, a nature that responded only to the boot and a short, upright, immobile tail. He called it Wagger.

When he returned to the inn he sat down at a table and ordered himself a dog's nose because it seemed appropriate.

The landlord, ajovial and mean man, sat down opposite him. "I suppose," he said, "I'm not allowed to know what this is all about."

Edmund Blackstone, Bow Street Runner, took the rusty pistol from his belt. "You suppose correctly," he said. "And should you try to find out – should you as much as lay a finger on my trunk upstairs. ..."

He cocked the pistol and together they listened to its knee-joint crack.

After his second dog's nose he went outside and, accompanied by his dog, attended to himself. He poured ale over his clothes, and rubbed his fingernails against the stone wall of The Naked Man until they were cracked and jagged. Then he dishevelled his hair, rubbing a little grease into it. The whole process offended him but he persevered, massaging soil into his hands until they had a dirty polish about them. He also applied a little dirt to his face, feeling a day's growth of stubble rasp under his fingers.

What else? His hobnail boots looked too new so he scuffed them in the dust. The dog stared at the boots, sizing up the enemy. What else? Blackstone's hands still bothered him because they didn't have the saddle-hard palms which you got wielding a shovel for twelve or more hours a day, but there wasn't much more he could do about them. Nor was there much more he could do about the styling of his hair, except attack it with a pair of scissors. He considered this and rejected it, wondering if he was making a mistake. He had made several recently and one more wouldn't surprise him; but still he didn't take the scissors to his hair – there were limits.

He knelt and examined the dog. It had a scarred muzzle and herring-bone ribs and exuded hatred; but when it curled its lip, which was often, its teeth were sharp and white. Blackstone fetched it some sausages. It swallowed them whole, reminding Blackstone of a snake swallowing small animals whole. After the meal the dog regarded him guardedly, thumb-sized tail unmoving. Then man and dog returned to the tavern looking as if they belonged to each other.

The girl had been crying and one eye was badly bruised. She was standing at the bar, plump breasts pushed against the woodwork. Blackstone sat down, ordered himself a pot of ale and listened.

"Just a little bread," the girl said. "And some ale. Surely you can spare that." Her face was ghosted with exhaustion.

"Let's see the colour of your money first," the landlord said. He was polishing glasses, lamplight gleaming on his jolly face. He grinned at Blackstone and winked. "Or had you some other sort of payment in mind?"

The girl sagged against the bar.

The landlord said: "You can't come into a tavern without a penny in your pocket and expect victuals." He held a glass up to the light and hung it above the bar. "Where have you come from? Shanty Town?"

The girl nodded. "I can't go much farther."

Her voice had London edges to it. The voice of the slums, the rookeries. Blackstone put her age at seventeen. But you couldn't tell. Sixteen, eighteen – she would be finished by the time she was twenty.

Blackstone said: "Give her some food and ale."

The landlord's hands froze on a tankard. His eyes set in cherubic flesh were bright blue. He hadn't resented taking orders from the elegant stranger who had arrived that morning with sovereigns jingling in his pockets; not even from the flamboyant navvy who had reappeared, because there was still an air of authority about him; but not from this unkempt moucher who had returned from the courtyard with his snapping mongrel. "Who says so?" he asked.

Blackstone considered his position. Navvies seeking employment on the Stockton and Darlington Railway didn't issue commands imperious with Bow Street authority. You didn't destroy your cover with the first harlot you met – a navvies' harlot at that; the mistakes had to stop some time.

The girl turned. "Yes," she said, "who says so?" She appraised Blackstone. "An out-of-work navigator? Come off it, my covey."

Blackstone searched the pockets of his velveteen coat. "I'll tell you what I'll do. I was going to have some bread and cheese. I'll share it with you."

She shook her head. "I'd rather dab it up with him." She pointed contemptuously at the landlord.

Blackstone sighed. What was one more mistake? He tossed two shillings on the bar. "Get her some victuals."

The girl threw the coins back at him. "Charity from a navvy? Not on your bloody life. I'd rather. ..."

But they had no way of knowing what she would rather do because she slid to the ground unconscious.

The landlord came round the bar and Blackstone said: "Keep your hands off her." He felt the girl's pulse; it was steady enough so he picked her up and laid her on a leather-padded bench beside the unlit fire. "Now get some food," he told the landlord.

When she came round there was cold mutton and bread and pickles in front of her and some gin and hot water. Her pride hadn't re-awoken and she ate ravenously. Blackstone poured hot water into the gin and pushed the glass across the table. She tossed the drink back, shuddered and stared at him resentfully.

Her face was pretty in a sulky sort of way; the sort of looks described as sluttish by those who don't know that sluttishness is an enforced occupation in the rookeries, preferable to skivvying or scrubbing doorsteps on raw knees. Her hair was reddish with a few ringlets still uncurled; her mouth was petulant and needed a smile; her pushed-up breasts were still firm.

After a few more moments of resentment she said: "Thanks." Her tone had little connection with gratitude. "And now what do you want?"

"Nothing."

"A navvy wanting nothing? Do me a favour."

"What's your name?"

"Dolly. Molly. Polly. Take your pick."

"Molly," Blackstone said. "Where are you from?" "You ask a lot of questions." She poured herself more gin and stared at him suspiciously. "Where do you come from?"

"The same place as you, I think. A long way from here. London. Holborn. The St Giles Rookery. Am I right?"

She relaxed a little. "You could be. I was born in a basement overlooking a dung heap."

"Ah," Blackstone said. "I remember that dung heap – we're neighbours."

She almost smiled. "Are you going to work on the S and D?"

Blackstone nodded.

"Don't bother, culley. Get back to the canals." She leaned across the table showing a lot of her breasts. "But there's something about you. You don't look as if you and hard work are partners."

Which was the trend these days, Blackstone reflected. Within five minutes of meeting a navvies' tallywoman she had spotted a flaw. Already the assignment had the familiar feel of failure about it.

First there had been the case of the Barbican swindler. Blackstone had chased him across the English Channel to Havre de Gras, always one step behind, then lost him. Blackstone was not ashamed of his efforts: Sir Richard Birnie, the Bow Street Magistrate, was. The penman had cashed a forged cheque for £400 and got away in a hackney carriage. One hackney to be traced among the hundreds in London. Blackstone asked Glindons to print handbills offering a reward to the driver and a man known as Boss-eyed Jack came forward. He said he had taken the penman to a flash tavern in Clements Lane. From there Blackstone traced him to the George Inn at Crawley, to Brighton where he had bought a gold watch for £35, to the Marine Hotel at Worthing; then Arundel, Chichester, Havant and the Red Lion at Fareham. Finally to Wheelers Hotel at Havre de Gras. Blackstone arrived just as the ship taking his quarry to New York cast off. "I onlyjust missed him," he told Birnie. "But you missed him," Birnie replied.

Then there had been the duel between two powdered aristocrats. Full of brandy and bravado the night before, they met at dawn the next day, palsied with fear. They aimed wavering pistols at each other, fired and missed and Blackstone didn't bother to take any action. They reported him to Birnie for failing to report them and Birnie said, "Two failures in a row."

They usually came in threes.

"When did you last do any hard work?" the girl asked.

"Never you mind," said Blackstone, awaiting the inspiration which had deserted him lately. It came to him, sluggishly. "You should see my hams," he said.

She looked at him mystified.

"You haven't been on the treadmill. You don't know what it does to your legs. It doesn't affect your hands." He showed her his dirty palms. "It's your legs that the treadmill fixes."

Her expression softened. "You've been inside?"

"The House of Correction," Blackstone told her.

"If you're on the run," she said, "take my advice – go to the canals. That's where the security is. There's only a couple of months' work left on this bloody railway. And you'll have to put up with Petro."