On a freezing November evening in the Cotswolds, Danny Dyer is calling on more than 30 years' experience as an actor to prepare himself to cope with the night of filming ahead. "You got to put them heat pads in your trotters," he says, gesturing towards his feet. "I've got two double ones for me toes," he continues, "and Long Johns obviously." We have been invited to the set of Rivals, the adaptation of Jilly Cooper's bonkbuster, which has generated exactly the kind of heat the cast and crew