It seems that (on Mock the Week at least) that he made some near to the bone jokes about someone.He was asked to tone down his humour,and said he would not,and therefore was asked to leave.
I imagine that the same applies to his appearances on 8 out of 10 cats.
I miss him on MTW.
NK.
Sadly the "powers that be" in the BBC decided that ALL of Frankie's output was unnacceptable,and if you have ever watched him if you cut out all of his "off colour" humour, there would be about a minute at the start,and a minute at the end.
So he went.