Just before Christmas, Sajid Javid performed a ritual he has observed twice a year throughout his adult life: he read the courtroom scene in The Fountainhead. To Ayn Rand fans, it’s famous: the hero declares his principles and his willingness to be imprisoned for them if need be. As a student, Javid read the passage to his now-wife, but only once — she told him she’d have nothing more to do with him if he tried it again. ‘It’s about the power of the individual,’ he says. ‘About sticking up for your beliefs, against popular opinion. Being that individual that really believes in something and goes for it.’

As Communities Secretary, he oversees the planning system and has embarked upon a new mission: addressing the housing shortage which he says has become one of Britain’s worst social curses. ‘The estimate is that there are at least two million people out there who can’t find decent homes and are being forced to live with parents or in overcrowded conditions. We’re dealing with a 30-year backlog.’ He aims to increase the number of homes built from 190,000 a year to ‘between 225,000 and 275,000 at least’. And so he has become the latest in a long line of ministers to promise to do something about a housing shortage.

Why, I ask, should we believe he’ll have any more success than his predecessors? ‘People are right to be a bit sceptical because they’ve heard it from governments over 30 years,’ he says. But Javid has new tools: more support for so-called factory homes — pre-fabricated buildings that he says ‘can be erected on-site within a week’. And the biggest constraint, he says, is ‘lack of the fundamental raw material’: land. This, he says, is where government can help. He plans a use-it-or-lose-it planning permission system to stop developers hoarding land while they wait for its value to rise.

More controversially, there will be a more muscular approach to councils who refuse planning permission; even (or, indeed, especially) Tory ones. Javid has said he’ll honour the party manifesto commitment to sparing the green belt, but there are exceptions — like 6,000 new homes recently authorised outside Birmingham, to the fury of the local Tory MP, former chief whip Andrew Mitchell. He promptly declared war on Javid and has been waging it ever since.

Javid expects more such wars, not just over housing but over the definition of Conservatism. ‘One of the reasons, or the main reason, I joined the Conservative party was to promote social progress and social mobility,’ he says. ‘The biggest barrier to social progress is our broken housing market. Fixing it means taking on a number of vested interests. It might make me a bit unpopular, but as long as I know I’m doing the right thing — which I do — then that’s what I’m in politics for.’

I ask about the property crash that was supposed to follow the Brexit vote, making homes much more affordable. He laughs, politely. He was an unexpected recruit to the Remain side, to the dismay of many Tories who assumed he’d been bought off by David Cameron. The truth is more complicated. Javid has always been a vocal Eurosceptic, but as the referendum approached he decided he could not go so far as backing Brexit.

He told me about his decision during the campaign. Part of him, he said then, would feel a great sense of elation at the freedom and opportunity if Britain voted to leave. But as Business Secretary, he believed the companies who told him of their fears about leaving. As a former banker, too, he feared for the City if financial firms were to lose their ‘passporting’ rights to do business across the EU. His decision was made with a rather heavy heart, knowing that, in such a polarising campaign, he’d please neither side and be portrayed as being all bark and no Brexit.

Has this episode damaged him politically? ‘I don’t look at it that way,’ he says, almost convincingly. ‘The way I see it, you pay a much bigger price if you don’t stand up for your beliefs.’

This is one of the many ways in which Sajid Javid is not a very good machine politician. He’s the son of a Muslim bus driver who prefers to let others talk about his roots — unlike another son of a bus driver, Sadiq Khan, the Mayor of London, who has a gift for dropping his background into every interview. The biography-is-destiny approach to politics has never appealed to Javid. He grew up in poverty but ended up as a vice-president of Chase Manhattan Bank at the age of 25 — he says he struggles to see what he has to complain about.

He found out a few years ago, for instance, that his early home life would nowadays would be categorised as homelessness — a family of seven cramped into two bedrooms. ‘But I would not pretend for a moment that I was homeless,’ he says. ‘I had a loving family, a loving home and a lovely environment to grow up in.’ Such restraint has its virtues, but could be seen as folly in an era when politicians are expected to blend what they say with who they are and where they came from.

Javid joined the party leadership race last year as the running mate of Stephen Crabb, whose cabinet career was brought to an abrupt end by a sexting scandal. When the winner, Theresa May, signalled a new direction for the Tories, using her party conference speech to attack the socialist left and ‘libertarian right’, it sounded as if she might have Ayn Rand-reading cabinet members in mind.

Javid suggests that his definition of politics is the same as Margaret Thatcher’s: about doing something, not being someone. He sees the Tories as the party of change and opportunity, and says such principles underpin his housing reforms — and if they upset fellow Tories, then so be it.

‘The Conservative party that I joined is not a party that stands up for the privileged and the moneyed,’ he said. ‘We stand up for ordinary hard-working people helping them to get on in life.’ And if this means a few more battles with Tory councils and MPs over where to build houses, then he is ready for the fight.