Will a jap import game play on a UK psp?

Depends what firmware you're running. I have a Jap PSP which plays UK games so I don't see why not. I'm on V. 1.5 (the one that allows you to play games from the memory card) and the games are just as good as if you're playing from a UMD.

have they managed to get new games to work like that yet royston?

Some of them do, Benjwaldo. I've got a DVD with several newish games on. To be fair I've not tried all of them I'm still enthralled with crashing cars on Burnout Legends. (30million dollars worth of damage so far!)

The newer games tend to take up more space as well. I have a 1GB memory stick, but Starwars takes up 2.3GB of space! what's all that about?

None of the PSP games are region locked so you can play any game on any PSP the trouble only arrises when you wish to play back up copies

None of the PSP games are region locked so you can play any game on any PSP the trouble only arrises when you wish to play back up copies

Yep, Jap games are actually the same region as UK I believe and firmware versions are the big hurdle with backup games.

Region encoding only applies to UMD Films.

I have a Jap PSP, my mate has a US one and we have a mixture of all region games which play on both machines with no problem.