I have faced the cavalry of Ayub Khan and ridden a war pony stolen from the Pashtu, as its owner swept down a rocky gully behind me, brandishing a rifle. I rode with Karim Bey across the Wild Pass in the Serbian rebellion of seventy-eight. I have seen a major in the Bengal Lancers take a wild pig through the fundament, only to have his spear bury itself into sun-baked mud beneath.

Good days. I miss them.

My name is Colonel John Hamish Watson, late of the Bombay Sappers and Miners. I know the weight behind a charging horse. I have faced it and lived. Four fine horses harnessed to a carriage whipped by one of the Queen's own coachmen carries enough force to smash a stone wall. So you will understand why I had little hope for the fool who stepped into my path on the high road through Kingston upon Thames.

There was, of course, little reason for my coachman to be whipping his horses so fast but I like to make my journeys at speed; the empire is large, the number of us who play the game surprisingly small and the rules complex, as you will realise from the fact I fought at Stara Planina with Karim Bey rather than the Serbs.

The first I knew of disaster was a shout from Hunter, followed by the frantic neighing of his horses and a thud. Something heavy catapulted across the roof of the carriage and tore varnished canvas above my head. A woman shouted, and the carriage tipped sideways.

We travelled maybe five paces before the first of the horses went down, tripping that behind. The scream of a wounded animal is something one never loses. It was such a scream, heard in the hills behind Kandahar, which convinced me Mr Darwin was correct and we did not, after all, rank between the angels and the animals. A man with his leg badly broken sounds little different to a horse in similar straits.

Using a window, which now showed only clouds, weak sunlight and the grey of an English sky, I crawled from the carriage, to find Hunter already knelt beside the head of a magnificent grey, tears in his eyes.

"Done for," Hunter said. "Legs, ribs... All broken." For Hunter this was almost a speech.

"Bad luck," I said. Undoing my loden coat, I loosened a holster that kept a Bulldog in place. "Here."

Taking my proffered revolver in silence, the coachman put its blunt muzzle to the side of his horse's head.

"At the back," I suggested, "or directly from the front. I can do it if you'd rather."

Hunter stared at me, although it's unlikely he saw much.

"Let me," I said, and when he looked doubtful, in as much as a face carved from Irish oak can carry that expression, I admitted something few people know about me. "I have a fine understanding of anatomy."

"You Sir?"

"I used to be a surgeon."

There are advantages in my world to being seen as a cold blooded killer, and to admit to saving as many as I had killed. Such admissions can do harm. Although the truth is far stranger, because I have killed fewer people than most believe and saved many more than I am prepared to admit.

Taking the revolver from Hunter, I clicked back the hammer and clambered across a broken shaft to reach the animal's head. Speak kindly and most people will give you their trust. The same applies to animals. With one hand I stroked the dying animal and with the other I put my revolver between its eyes and pulled the trigger. It died with a kick and a spasm, but the fact its skull contained myriad cavities did much to baffle the sound and gave me an idea for later.

"Thank you, Sir," Hunter said, thus using up another week's worth of words.

It was only then I remembered the unfortunate cause of our crash. I could see where he lay by the interest his agony attracted. A smaller crowd had come together around my wrecked carriage, drawn by its quality, but a far larger crowd was gathered a dozen paces behind this, and it was here the human cause and casualty of our accident lay.

They grew quiet at my approach, the crowd. Men fell back and women looked away, averting their eyes. A small girl burst into tears and a youth old enough to know better stared openly into my face. That was when I realised it was my revolver which earned their silence.

"You have killed me..." The voice was high, slightly strange and the man who spoke indeed looked on the edge of death, which was an improvement on what I had been expecting.

"It is always a bad idea to step in front of a moving carriage," I replied, unwilling to have him meet God believing the fault mine.

"Please," he said, "fetch me a doctor..."

He had the hollow face of a classics master and the fingers of a second violinist, somewhat bitten around the nails. Behind me, I could hear muttering and a woman bustled forward, mouth already opening to share her news. "A doctor recently took residence in a street behind." Several of the crowd began to agree, and one, a clerk from his dress, which was careful if none too clean, crouched beside me and offered to fetch this man.

I am a...

I almost said those words aloud, but instead I gave the clerk a guinea, to show the doctor his fee would be paid and told the man to run as swiftly as possible. Had I done what first occurred to me and announced myself a medical man, my coming retirement might have been very different.

"Tell your doctor to hurry," I said. "This patient needs urgent attention."