9pm, BBC2 If you wanted to make a film in the capital about the emotional bond between dogs and their owners, you could do worse than pitch up at Hampstead Heath ─ the biggest green space in London. In this funny, tough and affecting documentary, Vanessa Engle barks (personal questions) at assorted dogwalkers, who open up their lives; from the recovering alcoholic with a dog called Zen ─ "because he lives in the now" ─ to the woman who says of her dog, "Luna finds anything: bras, money, anything…" Pause. "Coats' heads." Ali Catterall