Extracts from Mitford’s papers published but many more archives concerning British fascists remain concealed

Myths and suspicions have swirled around Unity Mitford ever since she decided to move to Munich to pursue her infatuation with Adolf Hitler. Were they lovers? Did she have his baby? Why was MI5 forbidden from speaking to her when she returned to Britain?

Now, after extracts from the socialite’s diaries were published on Saturday , censorship campaigners and authors say the gatekeepers of Britain’s official archives should end their increasingly secretive approach to historical documents.