A film buff found a lost 1968 British TV movie about vampires that sparked a legend it was so terrifying it was marked for destruction, a preservation group announced. “No Such Thing as a Vampire” — one of six episodes from the short-lived 1960s BBC anthology series “Late Night Horror” — has been missing for more than half a century after it scarred viewers and caused an uproar that prompted the network to not only kill the show. But what is now believed to be the last surviving copy of the