If you’re not sure, leave it, goes the oft-repeated mushroom pickers’ mantra. Less known is the caveat: you can rarely be sure. There are no fail-safe tricks to identify a deadly mushroom. Even seasoned foragers carry at least three fungi field guides.

But Brigitte Tee, a mushroom picker for 34 years, whose clients include the Dorchester and Le Gavroche, said amateurs should still make the most of this autumn’s bumper crop.

She said that about 10 per cent of all wild mushrooms were poisonous, but most of them would merely “spoil your supper”. Cortinarius speciosissimus, or the deadly webcap, that Nicholas Evans consumed, is one of the few that will do more than that. But even so, Mrs Tee said, “if he has lasted this long, he should be able to survive”. Mrs Tee suggested that gatherers stick to common, species, such as porcini.

The most poisonous fungus is the Amanita phalloides, or death cap. It is responsible for 90 per cent of all fatal mushroom poisonings in Europe. Less than two ounces will cause vomiting, delirium, depression and almost certain death.

Explore Health News

• Swine flu

Times Recommends

• Times Christmas appeal: Letter from the Editor
• Conferences — what a waste of money
• Schools supremo learns a painful lesson