Michael Caine thinks that he has never said 'not a lot of people know that' but at least there is, or was, someone who says he did. This whole 'catchphrase' is from a Parkinson chat show with Peter Sellers who told how Michael Caine went through a phase of quoting statistics and comparisons from the Guinness Book of Records. He said that our hero would announce , for example, that if someone fell off the top of Big Ben clock tower he would hit the ground in (whatever) seconds. There would then be a silence from the bemused company which ended with Michael Caine saying, triumphantly, " Not a lot of people know that!"