Former British Prime Minister David Cameron is standing down as MP for Witney, triggering a byelection in the Oxfordshire seat.

Cameron's decision comes two months after he quit as Prime Minister on July 13 in the wake of defeat in the EU referendum.

Cameron said: "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 byelection and I will do everything that I can to help the Conservative candidate win that election.

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"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."

New Prime Minister May's paid tribute to Cameron.

"I was proud to serve in David Cameron's Government and under his leadership we achieved great things. Not just stabilising the economy but also making great strides in delivering serious social reform. His commitment to leading a one nation government is one that I will continue."

While Conservative grandee Lord Ashcroft believes it won't be long before Cameron is given a peerage for his services to the country, others were less than flattering about the former Prime Minister's legacy.

Former Cabinet minister Ken Clarke said: "I'm a friend of David's, so I regret to say, I think for history his legacy will be he's the man who accidentally caused Britain to leave the European Union.

"There's no getting away from the fact that that will overshadow every other feature of his premiership."

Labour leadership contender Owen Smith said: "David Cameron's legacy will be a country left reeling after six years of failed Tory austerity."

Len McCluskey, Unite general secretary, said: "While he may have decided to walk away the problems his austerity has created for the people of this country remain. His term in office will cast a long shadow over working people for generations to come."

Cameron said he wanted to continue making a "public service" contribution and would speak out about international issues in the future - a hint he may seek a new role on the world stage.