Nicholas Hammond was only 14 years old when he instantly gained a slice of cinematic immortality by playing Friedrich von Trapp, one of the seven singing siblings at the heart of the classic musical The Sound of Music. Now, 60 years after the film’s debut – and a lifetime of acting later – he admits that it wasn’t easy being in such a white-hot spotlight at such a formative age. “It was a joyous film to make. I’m enormously proud of having a small part in it and being a part of something that's brought so much pleasure to so...