Came out in the last 20 years or so. It’s not the very good The Guard with Brendan Gleeson (2011), although it might be a dark cop-comedy in that vein. I didn’t see the movie I’m asking about, but vaguely remember the trailer for it, and it looked good at the time. I thought Ray Winstone might have been in it, but I don’t see any such movie listed in his filmography.
This ring a bell for anyone? Thanks.
Are you sure it was a film and not an episode of a TV series? Like many UK actors he had a part in The Bill, a police drama.
Looking at IMDB, there’s Tough Love which has Winstone as a policeman.
No, that’s not it, thanks. Pretty sure it was a big-screen movie.
James McAvoy was in a 2013 movie called Filth, which is about a corrupt cop. Is that what you’re looking for?
No, I’ve heard of that, too, but that’s not it. Thanks anyway.
How about Pride and Glory from 2008? The corrupt cop in it is Colin Farrell and he’s Irish.
Also not it. Keep 'em coming, though - thanks!
Long shot - “In the Name of the Father” with Daniel Day-Lewis?
The Departed has Matt Damon playing Colin Sullivan. It’s been a long time since I’ve seen it, but that sounds like an Irish name to me. Was he?
Gary Oldman played a dirty cop in The Professional, but that’s mid 90s. In the same time frame, he did it again in Romeo is Bleeding.
Beyond those, the only other one I can come up with is Premium Rush. The bad cop is Michael Shannon, who is neither Irish or British, but always makes me think he’s something other than American. 
None of those either, Shoeless and faithfool. But thanks.
I’m now thinking it might have had something to do with an armored-car heist, but I’m not at all sure of that. My memory of the trailer is very hazy.
There are some bank jobs in 1998’s “The General”, with Brendan Gleeson (who I get mixed up with Ray Winstone, sometimes).
Face from 1997? Ray Winstone alongside Robert Carlyle, as gang members pulling off a big heist. Though it’s using a truck as a battering ram, rather than as the target. Part of the plot involves a corrupt police officer.
Most of that’s from Wikipedia. Despite having seen it in the cinema at the time, about all I could have told you from memory was that it was directed by Antonia Bird and had Carlyle in it.