'It was one of the most audacious acts of the Cold War which could have come straight from the pages of a spy novel. Georgi Markov was jabbed with an umbrella which fired a poison pellet into his leg as he crossed Waterloo Bridge. He died three days later – and for almost 35 years mystery has surrounded the whereabouts of his killer. Now the prime suspect has been tracked down to a small Austrian town where he works as an antiques dealer. Francesco Gullino, 66, who was known by his Communist handlers as 'Agent Piccadilly', lives in a rundown...