Cotherstone was out of his house from ten minutes to nine o'clock until five minutes to ten.

He was clearly excited when he returned: he was more excited when he went with the rest of them up the wood.

Was it not probable that under the stress of that excitement he forgot his presence of mind, and mechanically went straight to the all-important spot?
So much for that.

But there was something more.

Mallalieu was Cotherstone's partner.