The G20 has been a great showcase for our country and our capital city – and it’s been a great advert for the Olympics in 2012, showing that London is the place where the world can come together.

The critics wrote off the G20 as divided and undeliverable but the world came together to take action. I remember similar voices saying we could never get the Olympics to London and even if we did, our athletes weren’t a match for the best in the world.

The message sent loud and clear from London is – whatever the challenge – ‘yes we can’. I know we’ve all heard that slogan a thousand times but it resonated for President Obama – and for me it is still inspiring – because people instinctively want a better future for themselves, but especially for their children. And those better futures are achieved through a combination of government action to remove obstacles and create chances and individual effort and determination to seize those possibilities.

So ‘yes we can’ is not just a campaign slogan, it’s the reason why there are hundreds of young people training for their Olympic chance right now. And – believe it or not – it’s why leaders across the world, from Barack Obama to Gordon Brown to Kevin Rudd in Australia, first got involved in politics.

Of course, we have to make sure that the agreements we reached last week are enacted on the ground so they make a difference for the most hard-hit communities in Britain, where many families are struggling to keep their jobs and homes. There are people that still bear the scars from the recessions of the 1980s and 1990s, when millions lost their jobs and received no help to get back to work.

What is it that unites communities facing these hardships now? People tell me they want our country to get back its confidence and optimism by taking pride in what we can do. For businesses to say yes, we can invest here because there are the people with the skills that can make our company grow. People giving their own time and public servants saying yes, we will redouble our efforts to make this community stronger. Communities saying yes, we will stand together with the police and not let the anti-social or the criminal minority win. Whether it’s in sport, business or global affairs, Britain has always succeeded when we have taken pride – and shown ambition – in our country.

So that is why David Cameron makes me so angry touring the TV studios talking Britain – and that means the British people – down. It’s an easy thing for an opposition leader to do; find the worst in everything, to unpick progress and emphasise the negative. Yes, our country faces a tough time – but a cynical running commentary, without any solutions at all, just makes the situation worse.

They are always first to point the finger but the minute their own policies come under scrutiny, they shrink away from the spotlight. Before President Obama had even finished his summing up at the ExCel centre last week, David Cameron had dismissed the achievement of the G20 – but can you even begin to imagine him giving the world leadership and judgement on tackling the global financial crisis?

And his attacks on Britain are not just confined to the economy. David Cameron said that there were five million people in this country who were in danger of turning into Karen Matthews – nothing more strongly reflects his love of a good headline and his determination to do Britain down. With his Broken Britain slogan, he is talking down the hard work, the ingenuity, responsibility and good values of the vast majority of the British people. He should meet our Olympic heroes – not just those who will win medals for Great Britain but the thousands of volunteers who are already signing up to make London 2012 the best place in the world to be.

It may be in David Cameron’s short term interests to say Britain is broken and can never be fixed. It lets him slam the government and gives him an excuse not to offer people any real solutions. But it isn’t in Britain’s interests to give up and do nothing.

It is clear that the Conservative plan is to try to gain some advantage by relentlessly attacking the government recovery plan in general and the prime minister in particular. They do so not only because they have become incapable of putting the national interest above narrow party political interest, but because it is only by making increasingly shrill criticisms of Great Britain and Gordon Brown that they can hide the fact that they have no coherent or comprehensive response to the global economic challenge. But this strategy misunderstands where the people are: they rightly want ideas and answers, which address their anxieties, not rhetorical attacks which do Britain, and them, down.

Every part of our country is going through difficult times, but we will get through this recession. Now more than ever we should take pride in our country, believe in Britain and have the determination to succeed.