There was a long silence then, which I broke by checking something I’d been worrying about.

‘So you know that I’ll need some of his blood.’

‘Don’t tell your grandfather how to suck eggs,’ the doctor growled, then he gave me a tired smile and pointed down the lane towards Horshaw. ‘The mason’s on his way so you’d better get off and do your job. You can leave the rest to me.’

I listened and heard the distant sound of a cart approaching, so I headed back through the gravestones to see how the riggers were getting on.

The pit was ready and they’d already assembled the wooden platform under the tree. The rigger’s mate had climbed up into the tree and was fixing the block and tackle onto a sturdy branch. It was a device the size of a man’s head, made out of iron and hanging with chains and a big hook. We would need it to support the weight of the stone and position it very precisely.

‘The mason’s here,’ I said.

Immediately, both men left what they were doing and followed me back towards the church.

Now another horse was waiting in the lane, the stone resting in the back of the cart. No problems so far, but the mason didn’t look too happy and he avoided my eyes. Still, wasting no time, we brought the cart round the long way to the gate that led into the field.

Once close to the tree, the mason slipped the hook into the ring in the centre of the stone and it was lifted off the cart. Whether or not it would fit precisely, we’d have to wait and see. The mason had certainly fitted the ring correctly because the stone hung horizontally from the chain in perfect balance.

It was lowered into a position about two paces from the edge of the pit. Then the mason gave me the bad news.

His youngest daughter was very ill with a fever, the one that had swept right through the County, confining the Spook to his bed. His wife was by her bedside and he had to get back right away.

‘I’m sorry,’ he said, meeting my eyes properly for the first time. ‘But the stone’s a good ‘un and you’ll have no problems. I can promise you that’

I believed him. He’d done his best and had worked on the stone at short notice, when he’d rather have been with his daughter. So I paid him and sent him on his way with the Spook’s thanks, my thanks and best wishes for the recovery of his daughter.

Then I turned back to the business in hand. As well as chiselling stone, masons are experts at positioning it so I’d rather he’d stayed in case anything went wrong. Still, the rigger and mate were good at their job. All I had to do was keep calm and be careful not to make any silly mistakes.

First I had to work fast and coat the sides of the pit with the glue; then, finally, the underside of the stone, just before it was lowered into position.

I climbed down into the pit and, using a brush and working by the light of a lantern held by the rigger’s mate, I got to work. It was a careful process. I couldn’t afford to miss the tiniest spot because that would be enough to let the boggart escape. And with the pit only being six feet deep rather than the regulation nine, I had to be extra careful.

The mixture keyed itself into the soil as I worked, which was good, because it wouldn’t easily crack and flake off as the soil dried out in summer. The bad thing was that it was difficult to judge just how much to apply so that a thick enough outer coat was left on the soil. The Spook had told me that it was something that would come with experience. Up to now he’d been there to check my work and add a few finishing touches. Now, I would have to do the job right myself. First time.

Finally I climbed out of the pit and attended to its upper edge. The top thirteen inches, the thickness of the stone, were longer and broader than the pit itself, so there was a ledge for the stone to rest on without leaving the slightest crack for the boggart to slip through. This needed very careful attention because it was where the stone made its seal with the ground.

As I finished there was a flash of lightning and, seconds later, a heavy rumble of thunder. The storm had moved almost directly overhead.

I went back to the barn to get something important from my bag. It was what the Spook called a ‘bait-dish’. Made out of metal, it was specially crafted for the job and had three small holes drilled at equal distances from each other, close to its rim. I eased it out, polished it on my sleeve, then ran to the church to tell the doctor that we were ready.

As I opened the door there was a strong smell of tar and, just left of the altar, a small fire was blazing. Over it, on a metal tripod, a pot bubbled and spat. Dr Sherdley was going to use the tar to stop the bleeding. Painting the stump with it would also prevent the rest of the leg from going bad afterwards.

I smiled to myself when I saw where the doctor had got his wood from. It was wet outside, so he’d gone for the only dry kindling available. He’d chopped up one of the church pews. No doubt the priest wouldn’t be too happy, but it might just save his life. In any case he was now unconscious, breathing very deeply, and would stay that way for several hours until the effects of the potion wore off.

From the crack in the floor came the noise of the boggart feeding. It was a nasty gulping, slurping sound as it continued to draw blood from the leg. It was too preoccupied to realize that we were close by and about to bring its meal to an end.

We didn’t speak. I just nodded at the doctor and he nodded back. I handed him the deep metal dish to catch the blood I needed, and he took a small metal saw from his bag and laid its cold, shiny teeth against the bone just below the priest’s knee.

The housekeeper was still in the same position but her eyes were squeezed tight shut and she was muttering to herself. She was probably praying and it was obvious she wouldn’t be much help. So, with a shiver, I knelt down beside the doctor.

He shook his head. “There’s no need for you to see this,’ he said. ‘No doubt you’ll witness worse one day but it needn’t be now. Go on, lad. Back to your own business. I can deal with this. Just send the other two back to give me a hand getting him up onto the cart when I’ve finished.’

I’d been gritting my teeth ready to face it but I didn’t need to be told twice. Full of relief, I went back to the pit. Even before I reached it, a loud scream cut through the air followed by the sound of anguished weeping. But it wasn’t the priest. He was unconscious. It was the housekeeper.

The rigger and his mate had already hoisted the stone aloft again and were busy wiping off the mud. Then, as they went back to the church to help the doctor, I dipped the brush into the last of the mixture and gave the underside of the stone a thorough coating.

I’d hardly time to admire my handiwork before the mate came back at a run. Behind him, moving much more slowly, came the rigger. He was carrying the dish with the blood in it, being careful not to spill a single drop. The bait-dish was a very important piece of equipment. The Spook had a store of them back in Chipenden and they’d been made according to his own specifications.

I lifted a long chain from the Spook’s bag. Fastened to a large ring at one end were three shorter chains, each ending in a small metal hook. I slipped the three hooks into the three holes close to the rim of the dish.

When I lifted the chain, the bait-dish hung below it in perfect balance, so it didn’t need that much skill to lower it into the pit and set it down very gently at its centre.

No, the skill was in freeing the three hooks. You had to be very careful to relax the chains so that the hooks dropped away from the dish without tipping it over and spilling the blood.

I’d spent hours practising this, and despite being very nervous I managed to get the hooks out at my very first attempt.