UPDATE: Here's Sir Nicholas's letter to David Cameron...
Ann and I have been giving considerable thought in recent months to our future plans. While I remain tremendously involved both in the House of Commons and in my Macclesfield Constituency (and Ann is also much involved too) I am aware that we cannot maintain the hectic pace at which we have lived for nearly four decades and we would like a steadier lifestyle which would enable us to see more of our family, including eight grandchildren, not least at weekends.
Also with all the changes taking place in Parliament and in local government we feel that it is an appropriate time to announce that we do not intend to stand as candidates at the next general election and we will be notifying our Association Chairmen accordingly. However, I would ask that you do not make any public announcement about our decision until we have done this.
Parliament and my constituency have been my life for almost 38 years (and politics in general for almost 50 years) and in Ann's case for more than 26 years, but when you feel as we do that maybe the years are taking their toll and perhaps we can no longer represent Macclesfield and Congleton with the some level of energy and enthusiasm as in the past, we have reached the conclusion that we should pass the baton to a younger person because both Congleton and Macclesfield deserve the very best.
I hope that during the remainder of this Parliament I can help others in returning to the House of Commons itself some authority, independence and integrity over the executive of the day because the House is currently virtually impotent. Our support for the Conservative and Unionist Party is total and we will continue to do all we can to ensure a great victory at the next General Election whenever it comes.
We wish you every success.