I sat in on a Newsnight interview with Michael Caine the other day, as he was doing a show at the concert venue where I work.

One of the fascinating things he talked about - which didn't make the edit - was this ludicrous idea that he just plays himself on screen. Rather, he said, he's a bit like Fred Astaire: "You see Gene Kelly running up the walls and you say, 'I couldn't do that', but then you watch Fred Astaire, and he makes it look so easy - and you think, 'I could do that'. Trust me, you couldn't. And that's the same with my acting. 'I could do that.' Trust me, you couldn't."

That's true of his effortless, offhand performance in Billion Dollar Brain - the third instalment in the Harry Palmer series, which began with The Ipcress File (partly filmed outside the Hall!) in 1965 - lending a wit and subtlety to a film that starts with an utterly sublime scene nodding to classic noir, before declaring open war on our good will.

Part of the problem is the script, which features some fine speeches and delightfully sardonic Palmer zingers, but frequently introduces characters by having Caine simply say their name, too often plays for laughs, and has absolutely no substance: just a shrill, endless merry-go-round of double, triple and possibly even quadruple-crosses.

The cacophonous, bombastic music score doesn't help, either, especially when contrasted with John Barry's magnificent work on Ipcress, and Ed Begley's massive performance as a psychotic religious zealot can be safely filed under 'shit'.

It's sort of interesting, though, for director Ken Russell's familiarly frenzied, sexualised and operatic visual sense, some astute verbiage, and Caine's agreeable underplaying. You couldn't do that.