When champion pigeon racer Tom Van Gaver walked into one of his lofts one morning last November, he immediately knew something was wrong. Part of the door had been smashed from the inside. He soon realised it was no accident: thieves had broken into his aviary in Moortsele in Flanders and stolen five birds, including Finn, one of his most renowned breeders. Father and grandfather to many champions, Finn was “the Mona Lisa of the pigeon world”, Van Gaver said. The five birds, he estimates, were worth €750,000 (£625,000), but like da Vinci’s masterpiece, it is hard to tell, because…