Caroline Lucas, the Green MP for Brighton Pavilion, has told her constituents she will stand down at the next election.

In a letter seen exclusively by The Argus, she said that the intensity of her constituency commitments has meant she has "not been able to focus as much as I would like on the existential challenges that drive me - the nature and climate emergencies".

Ms Lucas, who is the UK's only Green MP, will remain in post until the next election, which is expected to take place in autumn next year.

Here is her letter in full:

Dear Brighton Pavilion residents and friends,

When I first stood to be your Member of Parliament back in 2010, I knew I was asking a lot of you.

It was the closest election for a generation, in the midst of the worst recession since the war, and after people’s faith in politics had been trampled into the mud of the expenses scandal.

Not the best time to come to people and ask them to take a risk and put their trust in a new kind of politics.

But on the day of the General Election in 2010, 16,238 people in Brighton did exactly that – and with the election of Britain’s first ever Green MP, together we made history.

It has been the privilege of my life to serve this extraordinary constituency and community, both those who voted for me, and those who did not, ever since – and to see my majority increase at each of the subsequent three General Elections.

And when I think back over the past 13 years, my strongest emotion is deep gratitude. Thank you so much to all those who put your faith in me and put the politics of hope above the politics of fear.

To every person who has stopped me on the bus and in the street to ask how I am and to share your personal stories, and who has offered encouragement as I have stood up in Parliament to champion your concerns and to hold this government to account, thank you.  

I love this city and its people, and I know how incredibly blessed I’ve been to have been given the opportunity to represent you, and to work alongside you.

I have always prided myself on being, first and foremost, a good constituency MP. The people who have come to me in my regular surgeries are often desperate, feeling like they have nowhere else to turn – they’re looking for care and compassion, not the tangled bureaucratic web that passes for a safety net, and that all too often just causes confusion and complication.

I’ve done everything possible to help wherever I can and always worked to ensure that people feel heard, that their concerns matter, and that they are not alone.

But the intensity of these constituency commitments, together with the particular responsibilities of being my Party’s sole MP, mean that, ironically, I’ve not been able to focus as much as I would like on the existential challenges that drive me – the Nature and Climate emergencies.

I have always been a different kind of politician – as those who witnessed my arrest, court case and acquittal over peaceful protest at the fracking site in Balcombe nearly ten years ago will recall. And the truth is, as these threats to our precious planet become ever more urgent, I have struggled to spend the time I want on these accelerating crises. I have therefore decided not to stand again as your MP at the next election.

I pledged that I would do my very best to do you proud. I can only hope that - whether you voted for me or not - you will judge that that is what I have done.

The reason I came into politics was to change things. Thirteen years ago it's inconceivable that Parliament would have declared a climate emergency; I’ve put issues like a universal basic income and a legal right to access nature on the political agenda; secured the first Parliamentary debate in a generation on drug law reform; and thanks to my work in Parliament, a Natural History GCSE will soon be on the syllabus.

I have said the previously unsayable, only to see it become part of the mainstream, on coal, on the myth that endless economic growth makes us happier, on a Green New Deal.

My determination to try to make change is stronger than ever. I look forward to having the time to explore ever more imaginative and creative ways of helping to make a liveable future a reality. Watch this space!

My heart will always be in this most special city, and with the inspiring communities and individuals I’ve been privileged to get to know. On election night 2010, I pledged that I would do my very best to do you proud.

I can only hope that – whether you voted for me or not – you will judge that that is what I have done.

With love and gratitude,

Caroline Lucas