It was outside a large, expensive-looking house with golden tips to the railings on the gate and a Rolls-Royce parked in the driveway that the Conservative party’s real London problem came into focus. The owners were British Indian. Freer pressed the buzzer. A woman’s voice responded:

“Yes?”

“Hello, it’s Mike Freer here, the Conservative candidate for . . .”

“We’re Labour, sorry, we always have been.”

Freer walked away from the door. “How can that be?” he asked me, exasperated. “Do they want to pay the mansion tax?”

At the 2010 general election, 68 per cent of Britain’s ethnic minorities voted for Labour. A woeful 16 per cent plumped for the Conservatives. In other words, the Conservative party is less appealing to non-white Britons than Mitt Romney was to non-white Americans in the 2012 US presidential election. In London, a city where white Britons are now in the minority, this is a problem. The Runnymede Trust, a think-tank, has yet to analyse the Black and Minority Ethnic (BME) vote at this year’s election but few expect drastic change.

While first-generation immigrants have tended to settle in central London, many of their children have decamped to the suburbs. This has given Labour a foothold in the outer London seats that were once solidly Conservative. The high cost of housing in the centre has only quickened the process.

Having won a miraculous majority and with full in-trays on their ministerial desks, senior Tories are unlikely to be putting too much thought to their problems in London anytime soon, but more is at stake in the city than 73 seats in the House of Commons.

Look at London and you are looking at the future of the rest of Britain. This is true not just in terms of ethnic diversity, but mindset too. According to the British Social Attitudes survey, today’s young adults — my generation — are more socially liberal, more individualistic, less community-oriented and more globally- minded then their parents and grandparents. In many ways, they are Thatcher’s children. But they will only vote for the right sort of Conservative party.

“Metropolitan” may be the political insult these days, but, whether the Conservatives like it or not, Britain is becoming more metropolitan. Young Britons think like Londoners. If the Conservatives don’t tackle their London problem it will become a Britain problem.