Wexford’s eyebrows went up. ‘Elucidate, please,’ he said.

Burden sat back, put his elbows on the arms of the chair, and pressed the tips of his fingers together. ‘A few days before this meal was eaten, Kingman and Hood met at the squash club of which they are both members. Kingman told Hood that Corinne Last had promised to get him some edible fungi called shaggy caps from her own garden, the garden of the house which they had at one time shared. A crop of these things show themselves every autumn under a tree in this garden. I’ve seen them myself, but we’ll come to that in a minute.

‘Kingman’s got a thing about using weeds and whatnot for cooking, makes salads out of dandelion and sorrel, and he swears by this fungi rubbish, says they’ve got far more flavour than mushrooms. Give me something that comes in a plastic bag from the supermarket every time, but no doubt it takes all sorts to make a world. By the way, this cookbook of Corinne Last’s is called Cooking for Nothing, and all the recipes are for making dishes out of stuff you pull up by the wayside or pluck from the hedgerow.’

‘These warty blobs or spotted puffets or whatever, had he cooked them before?’

‘Shaggy caps,’ said Burden, grinning, ‘or coprinus comatus. Oh, yes, every year, and every year he and Corinne had eaten the resulting stew. He told Hood he was going to cook them again this time, and Hood says he seemed very grateful to Corinne for being so – well, magnanimous.’

‘Yes, I can see it would have been a wrench for her. Like hearing “our tune” in the company of your ex-lover and your supplanter.’ Wexford put on a vibrant growl. ‘“Can you bear the sight of me eating our toadstools with another?”’

‘As a matter of fact,’ said Burden seriously, ‘it could have been just like that. Anyway, the upshot of it was that Hood was invited round for the following Saturday to taste these delicacies and was told that Corinne would be there. Perhaps it was that fact which made him accept. Well, the day came. Hood looked in on his sister at lunchtime. She showed him the pot containing the stew which Kingman had already made and she said she had tasted it and it was delicious. She also showed Hood half a dozen specimens of shaggy caps which she said Kingman hadn’t needed and which they would fry for their breakfast. This is what she showed him.’

Burden opened a drawer in the desk and produced one of those plastic bags which he had said so inspired him with confidence. But the contents of this one hadn’t come from a supermarket. He removed the wire fastener and tipped out four whitish scaly objects. They were egg-shaped, or rather elongated ovals, each with a short fleshy stalk.

‘I picked them myself this morning,’ he said, ‘from Corinne Last’s garden. When they get bigger, the egg-shaped bit opens like an umbrella, or a pagoda really, and there are sort of black gills underneath. You’re supposed to eat them when they’re in the stage these are.’