Until they didn't. The society osteopath Stephen Ward was scapegoated in the Profumo scandal and branded a pimp. Fifty years on, as Andrew Lloyd Webber turns his story into a musical, Xan Brooks goes in search of the truth " by talking to the people who knew him bestIn the case of Stephen Ward, the reputed pimp and puppet-master at the heart of the Profumo affair, history repeats itself first as tragedy and then…