South Cambridgeshire MP Heidi Allen has announced today she will step down at the next General Election.

In a letter to her constituents released on her website at lunchtime, Mrs Allen said that she had "could not have been more proud" to be elected as South Cambs MP in 2015, had "listened to your concerns, worked with others to fix problems, celebrated our area's incredible achievements and represented you to the best of my ability in parliament" - something she had loved doing.

Mrs Allen became a Conservative MP for the constituency in 2015, but resigned from the Tories earlier this year - citing Brexit and other issues with the party - and became interim leader of Change UK - The Independent Group.

She left Change UK in June, and stood as an Independent MP throughout the summer, before joining the Liberal Democrats earlier this month.

In her letter, she said the Brexit impasse made business as usual "impossible" over the last 18 months, and that Brexit had "broken politics".

Mrs Allen said that, more than all of that, she was "exhausted by the invasion of privacy and the nastiness and intimidation that has become commonplace".

She said: "Nobody in any job should have to put up with threats, aggressive emails, being shouted at in the street, sworn at on social media, nor have to install panic alarms at home.

"Of course public scrutiny is to be expected, but lines are all too regularly crossed and the effect is utterly dehumanising."

She said she was heartbroken, but that it was the right decision.

Ahead of the next General Election, which could yet happen before Christmas, she said she would continue bringing together the remain alliance through her Unite to Remain initiative - and said to change the trajectory of the country she believes "it's vital [Prime Minister] Boris Johnson and [Leader of the Opposition] Jeremy Corbyn are denied a majority".

Mrs Allen concluded by saying that she will work hard to represent constituents until her final day, and hopes she will pass the baton on to a new Liberal Democrat MP.

"To every consituent, thank you for giving me the greatest privilege of my life - to serve as your Member of Parliament," she said.

Below we have reproduced Mrs Allen's letter, titled to my South Cambridgeshire constituents', in full:

When I became your Member of Parliament in May 2015, I could not have been more proud. Since then, I have worked hard every day, listened to your concerns, worked with others to fix problems, celebrated our area's incredible achievements and represented you to the best of my ability in Parliament. I have loved being your Member of Parliament.

The children in our schools have energised me with their questions when I have visited them, their teachers humbled me with their passion and determination to develop the next generation, despite unacceptable funding pressures. I have seen our healthcare professionals care day in day out for our ever-growing population and our public sector workers make every pound count as they deliver the highest standards for local communities. I will never forget the shifts I spent with our police, ambulance and fire services; my gratitude for allowing me a window into their world of bravery and courage. The brains of South Cambridgeshire have tested my grey cells with their ground-breaking science and academic research. I have tried to keep up!

But for the last eighteen months or so, the Brexit impasse has made business as usual impossible. Brexit has broken our politics and it is my firm belief that only a confirmatory public vote will bring an end to this sorry chapter and bring healing and light at the end of the tunnel. Without it, we will continue to see the Conservative and Labour parties going round and round in circles, putting themselves ahead of the national interest.

And while Parliament has been in purgatory, we have legislated for almost nothing, changed almost nothing and improved almost nothing. I became an MP because I wanted to make a difference, but while Brexit continues to captivate Parliament, that just hasn't been possible. The reports I help to create as a member of the DWP select committee fail to arouse the attention of Government, debates about industrial productivity or funding our health service and social care don't happen and the system has ground to a halt.

I have been your representative for four and a half years. During that time, we have had an unprecedented two general elections, a referendum and unbelievably a third general election is now on the near horizon.

But more than all of that, I am exhausted by the invasion into my privacy and the nastiness and intimidation that has become commonplace. Nobody in any job should have to put up with threats, aggressive emails, being shouted at in the street, sworn at on social media, nor have to install panic alarms at home. Of course public scrutiny is to be expected, but lines are all too regularly crossed and the effect is utterly dehumanising. In my very first election leaflet I remember writing "I will always be a person first and a politician second" - I want to stay that way.

So, I have reluctantly come to the decision that I will not re-stand when the next general election comes.

I am heartbroken, but I know it is the right decision because I am no longer delivering the change that drove me into politics in the first place. I am proud of the significant improvements to Universal Credit I achieved, that I helped secure the passage of more unaccompanied refugee children from Europe and proud to have played my part in abortion reform in Northern Ireland. I am especially proud of my team who have supported me throughout. They have provided an exemplary service to my constituents.

And ahead of the next General Election, I will conclude the important work of bringing together a remain alliance through the "Unite to Remain" initiative I started after the European Elections. To change the trajectory of our country, I believe it is vital that both Boris Johnson and Jeremy Corbyn are denied a majority. I will work cross party in that endeavour with remain parties who are prepared to stand aside in the national interest.

In the meantime and until the final day, I will continue to work hard to represent you. But when the election comes, I will pass the baton on and dearly hope it will be to a new Liberal Democrat Member of Parliament.

To every constituent, whether you voted for me or not, thank you for giving me the greatest privilege of my life - to serve as your Member of Parliament.