For high end, and very accurate, go Kimber or T/C
I think the T/C is cheaper than the 552, though that 552 BDL is awful purdy!
In my experience, the most accurate .22 autoloading rifle is the Volquartsen rifle built on VQ's take of the 10/22 action.
A VERY expensive .22, especially once you add a scope that will do it justice, but it's hard to argue with that. I know a guy who gets nice little groups at 300 yards, but of course he's got a helluva scope and well over $2000 in the gun/scope combo AFAIK. I don't think that Odd Job was thinking about that sort of a purchase, though I could be wrong, and I don't want to think about the UK-markup over and above the US price.
The 597 Heavy Barrel with a Volquartsen trigger will get you pretty damn good performance for a fraction of the price. I hear they're hard to clean, though.
The 10/22's best features are reliability and simplicity. I like mine, a basic blue/recessed-synthetic version but I've decided to bite my lip and keep it stock except for a compact 4x scope and fiber sights for backup (factory carbine sights are not my favorite, especially when the gun's not in direct sunlight). It's my field knockaround gun, and it shoots quite well for the money. It shoots fine at 50 yards, with cheap ammo, as long as I clean it now and again.
One thing about the 10/22 is that you don't have to spend much money to get into it, and as you get pickier about long-range accuracy, you can upgrade it rather than replace it.
The Browning Auto 22 is a neat gun. Wierd looking, but it's actually got good ergonomics despite its appearance. Expensive, but it's a takedown. Might actually be available in Britain for a more reasonable price (relatively) than the US, since it's made by a European company.
People have said good and correct stuff about Marlins. I'll add this: I'd like a stainless Model 60 as one of my next firearms. Neat package, adult size stock. Like the Remingtons and the T/C it's made for a grownup, not a kid -- the 10/22 is a tad short, good for a compact field carbine but a little "scrunched-up" for a long shooting session: that's why most aftermarket 10/22 stocks advertise that they have a longer LOP.