‘It is still sappy. There are several. One quite close to the studio wall, and there’s another across the lane. If it should happen they were snapped off by the top of a vehicle, it must have moved from one side to the other. It is a fair chance, isn’t it, that they were broken by our van, and, if this is so, they give an idea of its height. Right?’

‘That’s right, sir,’ said Mr Sligo, breathing loudly through his nostrils.

‘You know all this sort of stuff, of course,’ said Alleyn, ‘but it’s a characteristic example of outside work. Now come along to the garage.’

They walked along the lane through a wide entrance into the garage yard. Alleyn unlocked the garage doors and broke the police tape. It had begun to rain steadily.

‘I took some measurements here last night, but it would be as well to verify them. Suppose you have a stab at it, Sligo.’

Sligo, intensely gratified, measured the width of the tyres and the wheel-base.

‘The tyres are the same, sir. Look here, sir, here’s the patch on the rear tyre on the driving side. We found the trace on the left-hand as you faced the window, sir, so she was backed all right.’

‘Good,’ said Alleyn. ‘That’s the way, Sligo. Now take a look at the doorstep. Wait a moment. I’ll just have a go at the handle for prints.’

He opened his bag and got out his insufflator. The grey powder showed no prints on the door or door-knob. Alleyn closely examined the three steps, which were worn and dirty.

‘Don’t touch these,’ he said, and opened the door.

‘Now then, Sligo—’

‘There they are, sir, there they are. Same marks on the top step. That’s the marks of them little wheels, sir, isn’t it?’

‘I think so. Check them to make sure. Here are the measurements of the scars on the window-sill.’

Out came Sligo’s tape again.

‘It’s them for sure,’ he said.

‘Now have a look on the roof. If you climb on that bench, you’ll do no harm. Go carefully, though. You never know if you won’t spoil a perfectly good bit of evidence in the most unlikely spot.’

Sligo mounted the bench like a mammoth Agag, and peered over the roof of the caravan.

‘Eh, there’s a-plenty of scratches, sir, right enough, and Gor’, Mr Alleyn, there’s a bit of a twig jammed between the top roofing and the frame. Dug into the crack. Gor’, that’s a bit of all right, isn’t it, sir?’

‘It is indeed. Can you reach it?’

‘Yes, sir.’

‘Take these tweezers and draw it out carefully. That’s right. Now you can come down. Let’s have an envelope, Fox, may we? We’ll put your twig in there, Sligo, and label it. How far is it from here to London?’