Misc: What U S president wrote 37 books?

Questions

UK 50s: _The Mousetrap_ opened its London stage run, but who wrote it??

UK 50s: In 1959, which party was elected for the third time in a row in Britain??

UK 50s: Robert Menzies was the Prime Minister of which country throughout the 50s??

UK 50s: Robert Menzies was the Prime Minister of which country throughout the 50s??

UK 50s: The 1951 Festival of Britain was centred on which city??