They say that in politics, if you're in a hole, you should stop digging. And yet there's something about the subject of British cinema that gets the prime minister repeatedly reaching for his spade. Perhaps it's something to do with Meryl Streep's Maggie gazing down from every bus, and maybe that film's sentimentalisation of a Tory leader has emboldened David Cameron to believe this is solid ground for him. He will keep on making these eye-catching and brazen announcements about British film – a topic on which, as Clement Attlee once said to Harold Laski, a period of silence on his part would be most welcome.

On Radio 4's Today programme, Evan Davis cheekily asked him to comment on a listener's view that in a Cameron biopic, Malcolm McDowell should play the lead (having famously played the public-school cad Flashman). Cameron opined that If … was a good film of McDowell's. Huh? Did Mr Cameron fully understand that Lindsay Anderson's If … was a searing attack on the public school system from a socialist director? Well, he was responding to a question, and he was caught on the hop.

But now he has made a calm and considered visit to the set of the new 007 film at Pinewood Studios and, on the occasion of a report into film-funding from Lord (Chris) Smith, that Blair-era figure who once wrote a solemn study titled Creative Britain, commented publicly that lottery money now needs to be targeted at "mainstream" films. Yes, of course, those commercial blockbusters and box-office sizzlers, as opposed to lefty chin-stroking arty-liberal fare (like, presumably, Lindsay Anderson's If …) Really, prime minister? What a bold new idea!

The sheer audacity is staggering. He says he wants to "build on the incredible success of recent years", but one of his administration's most sensational acts of party political grandstanding and spite was to cancel the UK Film Council – a creation of the Labour years – just when it was delivering not merely critically admired work but precisely those commercial hits of the kind Cameron professes to yearn for.

Could there be any better example of the classy, Brit-heritage smash than The King's Speech, a film which would not have existed without the UK Film Council's support? And yet just when this movie's producers were taking their Oscars away in a wheelbarrow, the Film Council was in the process of being wound up. It was the equivalent of David Cameron rushing on to the field at the final whistle of 2003 Rugby World Cup, calling for silence, and announcing that the coaching system was all wrong, and Clive Woodward and Jonny Wilkinson should be given their P45s right away.

I suspect Cameron now realises the UK Film Council move was one of his government's silliest blunders. It wasn't broke – so he broke it. Now he's returning to the fray, with some choice rhetoric about getting our British movie industry to up its game to rival Hollywood, a rhetoric he has learned from the Blair-Brown administration which, in fact, really did care about boosting cinema.

But it's not just a case of taking the "commercial"-looking projects and throwing money at them for higher returns. It doesn't work like that. Producing movies – any kind of movies – is a gamble. As the great screenwriter William Goldman said: nobody knows anything. The UK Film Council got it pretty wrong in the early years of its existence in chasing, and being seen to chase, commercial hits. It resulted in some embarrassing dross, chiefly about mockney gangsters.

Are we destined to go through this again? The UK Film Council was not perfect, and it certainly had its critics, but its successes were coming through the pipeline because it was always keen on self-scrutiny and research, always trying to get the balance between supporting crowd-pleasers and critical darlings. Because these go together, and the distinction is never clear in any case.

The challenge is to make good films, and to make as many as possible and to raise the statistical likelihood of success as high as possible. It may sound naive, but not as naive as this implied image of hearty commercial films starved of cash by lefty arthouse conspirators.

Cameron says he is against big government. Perhaps politicians like him will now resolve to leave the world of film alone for a bit.

• This article was amended on 12 January 2012. In the original Harold Wilson was attributed as saying "a period of silence", when in fact it was Clement Attlee. This has been corrected.