Imagine one of those fine days in early autumn when the sun is warm on your back but a brisk breeze promises to reawaken you after a drowsy summer. On such days, there are few things more entertaining than a fungus foray. Not a mushroom meander, or a toadstool tootle, or even an expotition to the North Pole (though the spirit is closest to the last), but a foray. I have had the privilege of going on two of these as a guest of a distant cousin, a botanist. Both were to the pine woods and dunes behind the almost endless expanse of Holkham Beach in north Norfolk. On forays, you and some companions each take a shallow basket and scour the scene for fungi of every kind. After an hour or so of pleasant rambling, you bring the finds back to base, where they are spread out on a blanket. Then you have a picnic. The hauls picked up by the experts in the party are astounding. How, you ask yourself, could I have missed those? ‘Only ninety species today,’ one says to another. ‘I’m sure we got a lot more last year.’

Richard Fortey has been a fungus forayer since boyhood and is now so expert he leads forays of his own, taking novice mycologists into woods and fields. This is, and has always been, a hobby. In his professional life he was a palaeontologist at the Natural History Museum, researching fossils