BRUSSELS – The lead singer of a British pop trio climbed a telecommunications mast behind the main stage at a Belgian rock festival and leaped to his death in the parking lot below, police said Saturday. Twenty-two-year-old Charles Haddon of Ou Est Le Swimming Pool died late Friday during the Pukkelpop festival in Hasselt, a town in eastern Belgium. District attorney Marc Rubens said police were treating the death as a suicide.