The invitation was for a day by the Thames crayfishing in the Henley area with chef Duncan Welgemoed, from The Five Horseshoes, Maidensgrove, but the recent floods ruled that adventure right out. Instead, we went foraging for crab apples, early blackberries and hogweed flowers in the nearby Russell's Water Common.

As the common is situated in the heart of the Chilterns, with only the flapping wings of red kites swooping overhead to disturb the silence, it proved the perfect place to forage for wild food.

Duncan's aim was to show me just how easy it is to find wild food to enhance the dishes on his menu.

Despite being only 23, Duncan is a chef with ambition. His sights are firmly set on gaining a Michelin star, which he believes is within his grasp thanks to his love of wild food and locally-sourced ingredients.

Born in South Africa, his inspiration comes from the many books he has read on the psychology of eating by greats such as Brillat Savarin, Escoffier, Anton Careme and even Collette.

He moved to England six years ago to meet and work with great chefs and has done just that.

Raymond Blanc and Heston Blumenthal rate among the many chefs he has met and worked with for a short period.

"I really cut my teeth working with Michael North, at the Goose, Britwell Salome, who I consider one of the great British chefs. For the first year it was just the two of us doing three sections as well as the potwash. Then we received the coveted Michelin star and all hell broke loose until the owner gave us permission to employ more staff", explained Duncan, who went on to work at the Pot Kiln, near Newbury, when the Goose changed hands. It was at the Pot Kiln that he worked with author, presenter and chef Mike Robinson, who taught Duncan to appreciate the joy of harvesting and using wild foods, particularly game and fish.

Duncan had intended to show me his specially-designed traps, bated with fresh fish bones, that yield a harvest of five to eight kilos of fresh signal crayfish each week when the river is not in flood. He uses the claws as the main ingredient in a bisque. The tails go into a salad. Only the heads are thrown away. As the signal crayfish, which is an escapee from America, threatens the existence of our native white-clawed crayfish, Duncan is confident that he's not only adding something tasty to his menu, he's helping reduce the amount of non-native crayfish in the Thames too.

Venison also features on his menu when it is in season. Once again Duncan gets involved by joining a local game keeper on the hunt and then butchering the meat himself at a registered premises.

Apparently venison is proving a favoured meat these days, mainly because it's local and virtually fat free. Saddle of roe buck, served with crushed sloes, creamed celeriac, radish and a veal vinaigrette is one of his most popular game dishes.

Locally-caught snails are another of Duncan's ideas. He goes for a large variety, which he finds on the common. Before snails can be cooked, the poisons in their bodies has to be flushed out. Duncan does this by starving them for a day and them feeding them fresh carrots. Within two days the colour of their droppings change from black to orange, which indicates they are clean and safe to cook. As carrots are antioxidants, Duncan says they are an excellent food for this purpose. Once the snails are clean, they are steamed for 20 minutes, then removed from their shells and braised in parsley and garlic for about six hours and finally served with a wild garlic puree after being roasted in foaming butter.

Because the earth was so wet, we didn't get down on our hands and knees and hunt for snails during my visit. Instead we picked up fallen crab apples, a few early blackberries, hogweed flowers, sloes and even some early mushrooms - agaric champetre - which are sometimes found in European pasturelands during mid to late summer.

The hogweed he picked is a member of the celery family (umbelliferae) and should not be confused with giant hogweed, which is much stouter and taller and can cause serious skin blistering when handled in bright sunlight. Hogweed has a distinctive and pleasant smell which is why Duncan enjoys using the flowers to flavour sugars and deserts. Hogweed is thought to get its name from its texture as the plant's stems and leaves are hairy, bristly even. When cooked this hairyness vanishes and the young stems have a delightful texture that comes without a hint of stringiness. Young leaves, flower peduncles and young stalks are what Duncan takes into the kitchen.

Obviously harvesting produce from the countryside is time consuming and there is no guarantee he will discover enough of any one item to warrant putting it on a menu. The wild fennel we found yielded but a few sprigs, just enough to garnish a couple of dishes. Duncan picked them nevertheless, just as he had picked the small sprig of agaric champetre and added it to the container. "They all help liven up a sauce," he said proudly.

Apparently he knows the area so well that customers are assured a gastronomic mushroom feast during the autumn when the nearby woods begin to fill with fungi.

He boasts of a secret place that he's discovered where even cepes flourish, but nothing, and I mean nothing, will prise its location from him.

The Five Horseshoes is not a large pub, but it can cope with the crowds on a fine day as there are seats in the garden where the view stretches for 30 miles in some directions. As there are some great walks nearby and this is a dog-friendly pub, Duncan hopes his passion for serving local ingredients and harvesting as much wild food as he can will attract customers who want to marry a country walk with a jolly good meal.