"People always think potatoes are tough plants, but they are actually very sensitive," says Saunders, strolling through greenhouses filled with sickly looking potato plants tended by young women in white coats. "They need to be constantly monitored from the moment they are planted to the time they are eaten." Such care demands a particular type of farmer and, once hooked, few ever return to less demanding crops like cereals. Every day he receives strange knobbly packages of worrisome potatoes, accompanied by a farmer's note asking for a quick diagnosis. Perhaps the seeds have a virus, or the main crop is showing signs of gangrene while in storage. Speed is essential to ensure that the crop is not lost.
The potato trials involve subjecting new varieties to as many nasty pests and diseases as possible. "We keep a big collection of diseases frozen in liquid nitrogen," he says, "so that we can assess the stamina of each new variety." He tips a plant out of its pot and carefully examines its roots. They are covered in tiny golden scabs, which are filled with the egg of every potato grower's nightmare - the golden potato cyst nematode. Once these drop off into the soil, the eggs will survive for 20 years and can devastate most varieties of potato.
Further trials are conducted outside, in NIAB's flat Cambridgeshire fields. "We choose different sites across England and Wales to see how different varieties respond to different soils and weather conditions," he explains, crouching to examine potato plant leaves for any sign of blight. Organic potatoes are proving especially challenging, because of their appetite for high levels of nitrogen and susceptibility to damage from aphids.
As most potatoes are marketed for a particular purpose, such as salads, baking or chipping, Saunders' department also examines the cooking qualities of each variety. It carries out blind tastings to assess a breed's particular texture and colour. Any tendency to disintegrate or blacken with cooking is noted, as is the final fry colour: pale golden is the in colour for chips and crisps at the moment.
"Although we trial about 150 new varieties a year, very few stay the course, despite the fact they are good," remarks Peter Saunders, rather sadly. But his troubles are soon forgotten once he has arrived home. A few new potatoes with a sprig of mint and a generous pat of butter, and he is a happy man once more