It's often said that, within 25 years, the turtledove will be gone from England's hedgerows. When they go, if they go, we will lose something that is a huge part of British culture – they are present in our folk songs and our poetry and for centuries the sound they make, a sort of sweet purring, has been synonymous with springtime. But in Suffolk, on the old road to Norwich, Graham Denny, a small-scale farmer is fighting to save them.    A love of turtledoves, he explains to Patrick, is something that he has shared with grandfather and his father and now he shares that love with his son. Graham has worked extraordinarily hard to turn his farm into a place where turtledoves thrive. His model is based largely on predator control, habitat creation, and providing food for the turtledoves to eat.    In this episode, Patrick sets off at dawn to visit Graham and to try to hear his doves purring.