It’s because they have to worry about stuff like this: http://www.dailymail.co.uk/news/article-4238188/Sir-Edward-Heath-paedophile-says-police-chief.html

The police chief investigating claims that Sir Edward Heath was a paedophile is convinced the allegations are ‘120 per cent’ genuine, The Mail on Sunday can reveal. More than 30 people have come forward with claims …

They have photographic evidence that shows he is a driver, and have established that he had a driving licence. He also bought a Rover 2000 after being deposed as Tory leader by Margaret Thatcher in 1975, when he was 58. Astonishingly, Mr Veale is also understood to support claims that Sir Edward’s alleged crimes were reported to police years ago but covered up by the Establishment. Some of those who said Sir Edward abused them are believed to have told police they went on to commit sexual abuse crimes themselves as a result. The investigation into Sir Edward, called Operation Conifer, was set up in 2015 in the wake of the Jimmy Savile scandal.

Look into the Jimmy Saville story. https://www.theguardian.com/media/2014/jun/26/jimmy-savile-sexual-abuse-timeline