Of course, a top provenance with a very limited supply is the North Star of the culinary firmament.
Tristan Welch at Launceston Place tells me that this week he has Denham Castle lamb, an ancient breed originally from the Shetland Isles and now bred near Newmarket, Suffolk. He's going to serve it with pea risotto and lamb crackling — very outré.
Good suppliers are a chef's lifeline: Jeremy Lee, head chef at the Blueprint Café, sources cobnuts from Allen's Farm in Kent, while Stuart Gillies, executive chef at Boxwood Café, has his sea purslane, hedgerow garlic and sea beet leaves hand-picked by a company called Forager in Canterbury.
Anthony Demetre of Wild Honey and Arbutus sources snails from Tony Vaughan in Herefordshire and uses them in his farinette of snails, which is an old French dish, much like a pancake, using sourdough, cheese, milk and eggs.
It's not just about British origin, of course. Sam and Eddie Hart at Fino are using whole suckling pig from Segovia in Castilla-Leon while Theo Randall tells me that he'll only use lemons for his lemon tart sourced directly from Amalfi in Italy, while his broad beans come from Cesena in Emilia Romagna.
For extra clout you can name a person. Frank Raymond at Mon Plaisir gets his fish from a M Condevaux, while his pigeons come courtesy of a M Mieral in Bresse.
But if it's names you're after then the one to drop at the moment is Jody Scheckter.
The former racing driver has created the first serious buffalo mozzarella in the UK on his farm at Laverstoke Park in Hampshire. He has a herd of Asian water buffalo.
I had some during lunch last week at Selfridge's with Ewan Venters, the store's director of food.
It was excellent. The good thing is that you can buy Scheckter's mozzarella and serve it at home, perhaps melted over some roasted muntjac. Now there's some serious culinary one-upmanship.
Simon Davis is director of the London Restaurant Festival (www.londonrestaurantfestival.com).
