Which is more shocking - Cameron resigning as MP or Mel and Sue leaving the Bake off?

Okay, so the title to this blog may be a little frivolous! I'll declare that I've rarely watched the Great British Bake Off so don't get what the fuss is about with the change in channel and presenters. Looking at all of the newspapers this morning, it clearly is a big thing. It would seem even more important than the former Prime Minister resigning his seat as MP for Witney!

Now, I know that part of the surprise with Cameron was that he said that he would continue as an MP until the next General Election. But then, he did say that he would continue as PM if he lost the EU referendum. You could see how he might become a distraction for Theresa May and her new Government, just as David Milliband would have been a distraction for his brother Ed when the latter won the Labour Party leadership.

It did get me thinking, though, what is the usual pattern for Prime Ministers once they have given up (either resigned or lost a General Election) in terms of remaining as an MP. Which former PM remained as an MP the longest? Is there a pattern? Do former party leaders really become a distraction?

So here's your Murnaghan-style pub quiz question for the day. Since 1970, other than Edward Heath (who continued from 1974 to 2001) who remained as an MP for the longest after they stopped being the Prime Minister? Don't include Harold Wilson's years as Opposition Leader.

Answer here.