Russell T Davies does not look as if he's just back from a wet weekend in Swansea. He bounds in, straight off the train and all glowing Californian tan, guffaw-punctuated anecdotes and booming, boisterous chat. Not that Davies is just about jolly asides and bonhomie. Back in London to promote the UK launch of Torchwood, the BBC spin-off series now reborn as a US premium cable show, the man who reinvented Doctor Who seems only too happy to fight the corporation's corner against a licence fee freeze that will see 20% cut from budgets.

"We all forgot how clever the Tories are, that's the start. We're all falling for how comic they are: the comedy of the coalition; Clegg and Cameron beside the hospital bed. They're fooling us into thinking they're funny – but they're not, they're viciously clever people," he says.

"And who can complain when they introduce massive austerity measures and then, 'Oh, by the way, we're crippling the BBC at the same time'. Because of course we're manning the barricades for the hospitals, the children, for food – never mind television."

It is almost impossible not to be swept along as Davies gets stuck in – he manages to somehow combine good humour with tough argument, to be absolutely convincing while remaining perfectly genial. He seems almost more disappointed than furious. He might make a good politician himself.

"What I thought would be a huge debate and have the public storming the ramparts was brilliantly sidelined," he observes. "How clever, how clever, were they? I thought that would be a national argument – and it's just agreed. It's done. It's going to get worse, of course it's going to get worse. My God, they're frightening."

Funding model

Davies's defence of the BBC is all the more interesting given Torchwood's new funding model. What was previously a BBC Wales show is now a three-way co-production with the corporation's commercial arm, BBC Worldwide, and Starz (best-known for Spartacus: Blood and Sand and Camelot) – with the US broadcaster providing the lion's share of funding. "It's a brand new model," he says cheerfully. "Starz own the greater rights, but it has me there to make sure it doesn't become a prostituted version of the show – which nobody wanted anyway, but you've got to have somebody steering the train – and who knows if it will work?"

Central characters Captain Jack and Gwen remain, and some of the action still takes place in Wales – but in terms of actors, locations and effects, the show feels noticeably more American. Torchwood fans will already be used to Captain Jack's American twang, of course, which Davies hopes might provide "a window there, a kind of way through". But he admits it might be slightly odd. "I watched it sometimes myself and some – well a lot – of the scenes were just the Americans without a single English or Welsh note, and you think, how's that going to play out on BBC1?"

Audiences in the US will now get to watch Torchwood before those in the UK. And while it's not yet clear how long British viewers will have to wait for the show, it may be up to a week – which sounds rather like a recipe for illegal downloading. But Davies, never over-enamoured of the views of hardcore superfans, seems largely unworried about the possibility – arguing that as it's a BBC1 9pm show, not many will bother to download it first.

Seeing shows after the US could be, in any case, something that viewers might have to get used to: in the current climate, such co-productions make financial sense. (And, as Davies points out: "All those Dickens shows have been co-productions for about 20-odd years and we don't question it"). LA-based BBC Worldwide Productions, headed by Jane Tranter, who commissioned Davies's Doctor Who revival when she was BBC head of drama, is there to pioneer more of the same.

Tranter recently talked about an "editorial simpatico" between BBC and cable broadcasters and Davies echoes her views. He describes the similarity between the BBC and premium cable channels such as HBO and Starz – who want "dramas that aren't just doctors and nurses and lots of happy endings"– as "a godsend" and a possible future model for more British television.

"We're going to try and make more and more different stuff out there," he says. "The very interesting thing will be, what if it does well on Starz but doesn't do well on BBC1? Or if the BBC1 money is tight and they have to take money away – does it become entirely a Starz production, which means they have to own the rights? Would the BBC do that? Would they actually give away rights to an existing property?"

Davies moved to the US after handing over Doctor Who, which he revived to great acclaim, to Steven Moffat and his new doctor, Matt Smith ("Oh I love him. He's limitless, isn't he?"). The main difference between working in US and UK television, he says, is – predictably – money, although he claims he hasn't learnt to spend money over there "because we haven't had it".

"We've got a lovely budget. We had roughly twice the budget [of previous Torchwood series] but then everything costs twice as much, and you work twice as hard to stop it being spent," Davies says. "You wrangle over money far more than I have ever done here."

The energy and upbeat tone suggest Davies wouldn't have it any other way. However, at one point, he suggests this series of Torchwood may be his last. "In theory I could have handed it over to a bunch of strangers and said good luck to them – and if there was another series I might do that because I think there's only so long you can spend doing Torchwood."

And how long is that? Davies almost immediately backtracks. "I say that," he laughs, "I start the series and I think, I'm never doing this again." But then he relives his brilliantly theatrical response last weekend in Swansea, his hometown, when looking at an edit of the last episode of the show, which this series has lost a lot of its monsters in favour of a longer, more conceptual story arc.

"'It's so marvellous! It's so marvellous!'" he laughs again. "It's hugely exciting and I've got to do this again. I've got one more story that I can tell – just one more that has Gwen right at the centre of it – that would be fantastic. So I'm my own worst enemy."

Davies's excitement at his own show is mirrored by his clear delight in television in general. He watches lots. Our conversation takes in, amongst others, Game of Thrones, Scott & Bailey, Saturday Kitchen and The Good Wife ("To me, it's the new West Wing"). And, of course, his beloved Coronation Street. "The only odd thing I felt about moving there [the US] to live was the television, because it's very strange. My God, you miss your evening soap opera. When you've watched it all your life, 7.30pm is soap opera time."

In fact Davies still manages to get his weekly dose of Corrie, albeit in an omnibus style, but he thinks US television, so skilful in other areas, suffers from an absence of primetime soap. "When it comes to domestic stuff, they can sometimes be quite crude, quite lacking, because they haven't had 50 years of Coronation Street. They don't pipe every divorce, every birth, every wedding and every funeral into your house five times a week."

He's hilarious on the subject of US Saturday night TV, when, he says there is nothing on television. "Nothing! Nothing! Repeats of stuff in the week!" Why do executives think everybody is out every weekend, he wonders. "They're not. I'm not. I bet you're not. Anybody with a family isn't. Students aren't."

What the US schedules need is something like Glee to play on a Saturday night, Davies says. But surely this is a perfect opportunity for Davies to repeat his Doctor Who trick, I suggest. He laughs: "It does feel like Doctor Who when people said it would never work because you couldn't play a drama then."

I wonder whether he misses Doctor Who. "I don't, because I did it so often," he replies. "I don't miss anything. I don't miss Queer as Folk. Once you've done something, you just move on. You miss them, I love what I did. But that's not missing it, is it really?"

Davies, who wrote for ITV kids' drama Children's Ward, is thinking about another children's show. The Sarah Jane Adventures, the CBBC series he created, has ended after the death of Elisabeth Sladen.

"We loved her," Davies says of the actor, adding that the team couldn't bear to do any kind of spin-off that didn't have her in it: "It just wouldn't be comfortable." But the production team would like to create another show for children. "That's the best audience that you'll ever work for. Make a good kids' show and they'll remember it when they're 80."

There are Doctor Who fans who would doubtless agree.

Torchwood: Miracle Day will be on BBC1 next month