Will a spent criminal conviction affect my chances of getting a funded PhD position? I am in my third year of a Mathematics degree (UK). Where a masters is concerned, It seems like I only have to declare unspent convictions. But it is not clear where research positions are concerned.

It is spent now, has been for 12 months. I had 50 hours community service for the crime (Not a custodial sentence).

The research I would be interested in doing would be in either Applied Mathematics(Physical fields) or Computer Science. I feel ill whenever I talk about it. 

The offence was an assault. I pressed charges, so did he.
Also I am interested in UK/Euro universities, not America. 

Could anyone shed some light on this? maybe someone who may have applied for research positions in these fields?

If this is the wrong place to ask this question then please say so I can remove it.
I do not know about the legal situation, but from my experience from hiring and scholarship committees I would say that everything not affecting your work at university has little influence on your chances. So a pub fight gotten out of control or an excessive reaction to some perceived provocation would be no problem, theft of university equipment or sexual harassment would be a problem. In any case, not being open about whatever you did will bring you into trouble. Academia is a small world, chances are that I meet someone who knows you next time I come to England. Rumors do spread, and are usually far worse than the truth.