Below I've reproduced the text of her resignation note to the constituency chair, Tony Fradley.
I wanted you and the General Committee to be the first to know that I have decided not to seek re-election to Parliament at the next General Election in 2015.
As you can imagine this has been a decision I have not reached easily and has only been possible after a lot of soul searching. But, hard as it is to imagine, I shall be 71 at the end of the next parliament. Given the demands of constant travelling, working from both the constituency and in parliament, working weekends and long hours, I think that 2015 is the right time for me to hang up my boots.
I remember vividly the meeting in 'The Leopard' when I was chosen as the candidate to represent the Labour Party in the 1987 election. When I signed the acceptance on the nomination forms I used a cardboard advertisement from the brewery to rest my papers on. Its words were 'You have just won the opportunity of a lifetime'. Indeed I had. Not many MPs have the privilege of representing the area they are brought up in and belong to and I have been privileged to have had the local party's backing to do this since 1987. All officers of the party have been outstanding in their support of me but none more so than the ever-constant secretary Neil Dawson whose local knowledge, wisdom and commitment is second to none. I am also always aware that without the love and support of my family I could not do the job I do. For that I am truly grateful.
Environmental and health concerns have always been my priority and I have worked to secure advances in public health and well-being, working with local and national groups and the last Labour Government on this long-term agenda, including the rebuilding of local schools and Haywood Hospital. The return of the Kidsgrove wards to the constituency following boundary changes in 2010 has added a whole new dimension to our work and I hope we can succeed in various efforts to improve Kidsgrove, not least the bid for disabled access to the Railway Station. I have always sought to work alongside local people and businesses to enhance their ability to invest and bring the improvements the local area needs.
Investing in the right policies to secure the future we want in environmental terms - tackling environmental degradation and valuing nature - has always been and remains my mission. I regard my election by parliament to chair the Environmental Audit Select Committee as a great honour. You can be in no doubt that my chairmanship of that and indeed my work as constituency MP serving the interests of people here will continue right up until the referee blows the final whistle and the General Election is called in 2015.
I wanted to tell local members first and have done so now so that you have sufficient time to consider and decide the successor of your choice. I wanted to make sure that whoever the candidate is, they and you have time to prepare for the 2015 General Election and to win convincingly. In 2015 Stoke-on-Trent North will need a Labour MP more than ever.
Over my 26 years in parliament so far I have seen many changes and worked with many people over the years - some sadly no longer with us (Harry Edwards and John Locket amongst many) - with trade unions, community groups and institutions. I always have and always will value the support they and all of you have given and continue to give me.
This is not an easy decision as I feel as passionately as ever about my work. However, nothing lasts forever. I very much appreciate and count on your continued support. It goes without saying that I shall be out there working for a Labour Government and supporting our leader Ed Miliband to bring about the change our country and our city so desperately needs.
Yours in solidarity,
Joan Walley MP
Labour Member of Parliament for Stoke-on-Trent North
Chair Environmental Audit Select Committee