David Cameron has resigned from parliament.
The former prime minister announced he was stepping down as MP for Witney with immediate effect.
It comes nearly three months after he resigned as the country's leader in June following the UK's vote to leave the EU in a national referendum.
Mr Cameron told ITV News that he had thought "long and hard" over his choice but had ultimately decided that he would be a "distraction" from the work of government.
Video report by ITV News Deputy Political Editor Chris Ship
In my view, with modern politics, with the circumstances of my resignation it isn’t really possible to be a proper backbench MP as a former prime minister.
Mr Cameron said that he had informed Theresa May of his decision this afternoon and she was "very understanding".
He denied that his last political legacy would be as the man who took Britain out the EU.
"I’m sure I will remembered for keeping that pledge to hold a referendum when many people thought that promise would never be kept," he said, adding that he had also overseen social reform and sought to modernise the party.
His resignation will trigger a by-election.
"Obviously I’m going to have to start to build a life outside Westminster," he said as he announced his decision in Witney.
"I'm only 49 and I hope I can still contribute in terms of public service and contribute to our country."
He added that he will continue to live in Witney and that it had been a "honour" to serve the area.
Mr Cameron also released a formal statement confirming his decision to stand down.
I spoke this morning to the chairman of the West Oxfordshire Conservative Association and I have just come from a meeting with my constituency agent and other members of staff. Having fully considered my position over the summer, I have decided that I am going to stand down as the Member of Parliament for Witney. There will now be a by-election and I will do everything that I can to help the Conservative candidate win that election. In my view, the circumstances of my resignation as prime minister and the realities of modern politics make it very difficult to continue on the backbenches without the risk of becoming a diversion to the important decisions that lie ahead for my successor in Downing Street and the Government. > I fully support Theresa May and have every confidence that Britain will thrive under her strong leadership. It has been an honour to serve the people of Witney and West Oxfordshire for the last 15 years. I want to thank them for making the job of representing them such a pleasure and a privilege. I would like to thank the party workers, volunteers, councillors and supporters for all they have done to help me. Our house in Dean is the place Samantha, my children and I call home, and that will not change. I will continue to support the local causes and charities that mean so much to me and many others in this beautiful and enterprising part of our country. I now look forward to a life outside of Westminster, but hope to continue to play a part in public service and to make a real and useful contribution to the country I love. >