Select Committee report says the former PM's intervention in Libya spurred the growth of Islamic State and triggered the refugee crisis.Read the full story ›
Former prime ministers have found that not only does life go on after living at Number 10, but in some cases it actually gets better.
The most recent men to vacate office have shown it can certainly be very lucrative.
Tony Blair made millions from his autobiography and for eight years represented the US, Russia, the UN and the EU as a Middle East Envoy.
He also reportedly earns £250,000 per speech.
Gordon Brown gets a reported £65,000 as an after-dinner speaker and is the United Nations special envoy for education.
Mr Cameron may remain motivated by the public service ideals that drove him into politics, becoming an advocate for a single issue, which would also serve to repair a political legacy badly damaged by the EU referendum result.
If he wants to make money he can go into business knowing he will no longer have to declare the source of his earnings as all MPs must do.
Mr Cameron will also be expected to pen an autobiography or political memoir on his time in Downing Street or perhaps follow other leading politicians into novel writing.
And, of course, there are world lecture forums or the after-dinner circuit that have proven so popularly profitable with his predecessors.
Labour leader Jeremy Corbyn said he wished David Cameron "all the best for the future", adding he got on well with him on a "human level".
Mr Corbyn thanked the former prime minister for the "courtesy" he showed him.
He added: "We should respect people who move on to do something else with their lives. I want to wish him all the best for the future."
Speaking as he arrived for a private dinner with the TUC general council in Brighton, Mr Corbyn also joked about the "advice" Mr Cameron said his mother would give him about what to wear.
He also said he wanted to wish him well as a fellow cyclist, but joked he wasn't going to say "on yer bike."
David Cameron's legacy will be "overshadowed" by his role as the accidental architect of Brexit, according to the former Conservative minister Ken Clarke.
"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, he told BBC News.
"There's no getting away from the fact that that will overshadow every other feature of his premiership."
Mr Clarke added that he was "disappointed" by Mr Cameron's decision but said the "chickens came home to roost" after the referendum.
The Scottish Conservatives leader has indicated that she will not seek to take David Cameron's place as the MP for Witney after he stood down today.
Ruth Davidson was seen as a potential front-runner for the safe Conservative seat.
However she threw cold water on the speculation by saying anyone thinking of betting on her taking the seat should 'save their money'.
George Osborne has said that David Cameron's resignation from parliament is a "sad day" in a tribute to his key political ally.
Osborne, who served as treasurer under Cameron, said he was sad to see his "great friend" leave British politics.
"I will miss him alongside me on the green benches over the coming years," he wrote on Twitter.
Sorry to see my great friend @david_cameron stepping down - he loved being Witney's MP; I know how difficult this decision has been for him
We came into Parliament together, had a great partnership + I will miss him alongside me on the green benches over the coming years. Sad day
The Liberal Democrat leader has praised Mr Cameron for forming a coalition government but said his main political legacy would be taking the UK out of Europe to the "huge detriment of future generations".
Tim Farron said that the former prime minister had "demonstrated a capacity to think above and beyond tribal politics" by creating the first post-war coalition government between 2010 and 2015.
He also praised Mr Cameron's qualities of "personal courtesy, humour and thoughtfulness" but said the former leader would be mainly remembered for taking the UK out of the EU in a damaging "gamble".
He has lots of things that he should be proud of but sadly his legacy will be one of accidentally removing us from our closest friends and neighbours in Europe.
He took a politically motivated and short-termist gamble with our country's future, and lost to the huge detriment of future generations. He now leaves the rest of us to pick up the pieces.
Theresa May has said she was "proud " to work in David Cameron's government as she thanked him for his service to the country.
The new prime minister said that the Conservatives had achieved "great things" under her predecessor as he resigned from parliament.
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 lead a one nation Government is one that I will continue – and I thank him for everything he has done for the Conservative party and the country.
I wish him and his family well for the future.
Former Conservative leader William Hague has praised David Cameron for his decision to stand down as an MP.
Mr Cameron has said that he did not want to become a "distraction" from the work of Theresa May's government.
Mr Hague agreed, saying former prime ministers were either viewed as a diversion or accused of doing too little.
Right decision by David Cameron to leave Commons - former Prime Ministers are either accused of doing too little or being a distraction.