The full text of Andrew Mitchell's resignation letter to David Cameron and the Prime Minister's written reply.

Dear David,

It is with enormous regret - not least because of the tremendous support and loyalty you have shown me during recent weeks - that I am writing to resign as your Chief Whip.

Over the last two days it has become clear to me that whatever the rights and wrongs of the matter I will not be able to fulfil my duties as we both would wish. Nor is it fair to continue to put my family and colleagues through this upsetting and damaging publicity.

I have made clear to you - and I give you my categorical assurance again - that I did not, never have, and never would call a police officer a "pleb" or a "moron" or used any of the other pejorative descriptions attributed to me. The offending comment and the reason for my apology to the police was my parting remark "I thought you guys were supposed to f***ing help us".

It was obviously wrong of me to use such bad language and I am very sorry about it and grateful to the police officer for accepting my apology.

I am immensely grateful to you for giving me the opportunity to serve as your Development Secretary for seven and a half years, both in Opposition and in Government.

I believe Britain, under your leadership, has made real progress in transforming the lives and the opportunities of some of the world's poorest people and that we will continue to do so as we deploy an expertise and commitment which show Britain at its best.

I now intend to concentrate on serving my constituents in the Royal town of Sutton Coldfield to the best of my ability and giving you the strong support you rightly deserve from all members of the Conservative Party.

With every good wish,

yours ever,

Andrew Mitchell.

>Next page: The Prime Minister's reply to Mr Mitchell.

>More on this story: Andrew Mitchell quits