David Cameron vowed last night to put "hard-headed" commercial interests at the heart of his foreign policy by reaching out to booming nations in the developing world.
He also argued the country needed to take a more pragmatic view of its place in the world, warning Britain had over-reached itself and not properly planned for the wars in Iraq and Afghanistan.
Making his first annual Mansion House speech on foreign affairs, the Prime Minister argued Britain was failing to sell enough goods to the burgeoning middle-classes in Brazil, Russia and Turkey. He said: "We are not making nearly enough of the opportunities out there. Some people think it is somehow grubby to mix money and diplomacy. I say: when it is harder that ever for this country to earn a living, we need to mobilise all the resources we can."
The PM said he will travel to Brazil and Russia next year to try to forge new trading ties.
He said: "In recent years we have made too many commitments without the resources to back them up. So in Iraq there was no plan for winning the peace. In Afghanistan we failed to think through properly the implications of the decision to deploy into Helmand province in 2006."
On Afghanistan, Mr Cameron repeated his commitment to withdraw British forces by 2015, stressing the limits to the impact that western intervention could have.
He said: "We are not there to build a perfect democracy, still less a model society.
"We are there to help Afghans take control of their security and ensure that al-Qa'ida can never again pose a threat to us from Afghan soil."
William Hague, the Foreign Secretary, yesterday said that it was a "very, very" long-term target to wrest back control of every valley in the country.