Walk through the neat, green rows of apple trees at Linvilla Orchards, the 335-acre, family-run farm outside of Philadelphia, Pennsylvania, and you'll spot a little white sign that reads ...

"Apple fruit production in the UK is not that big a business," explains Ordidge ... their flesh is cream-coloured or greenish-white, and their names – Black Gilliflower, Bridstow Wasp, Eggleton ...