FREE-RANGE POULTRY, YORK: Brought up on the 1200-acre (486-hectare) family farm north of York and having milked cows from the age of eight, David acknowledges that farming runs in his veins. Today the farm combines dairy, poultry and arable, but it's the poultry side of things that David looks after. He manages three free-range laying sheds, each housing 26,000 birds, and also runs a rearing unit producing pullets (young female chicks).

David is keen to make his poultry business as sustainable as possible, using a 'circular' system of farming whereby the farm produces up to 70 percent of its own chicken feed. He does this by growing wheat, barley and oil seed rape which are milled on farm then fed to the hens. Those crops are in turn fertilised with chicken manure that David puts back on the land. He estimates the farm produces around 1500 tonnes of poultry manure a year, reducing his use of synthetic fertilisers by around half on some areas of the farm.

David turned a disused chicken shed into a rearing shed, which is heated by wood chip boilers. These are one of several forms of renewable energy used on the farm, which also generates hydroelectric power and uses solar panels. Rearing his own pullets (from one-day-old chicks which are bought in) means David can control of all parts of the poultry business while also reducing costs and carbon emissions.

He is currently doing a Nuffield Farming Scholarship, looking at how to add value to the poultry manure produced on farms. For this he has travelled to Austria, Slovenia, Gran Canarias, New Zealand and the Netherland to learn new ideas and technologies.

David is also a dab hand at engineering, especially welding and fabrication, and is often to be found tinkering in his workshop if he ever has spare time. Engineering is what David studied at university. He is gradually taking over the reins from his dad, who is now semi-retired.