Can you appeal decision not to prosecute?

[questionmaster]

My friend was recently badly assaulted and knocked unconscious in an unprovoked attack. He required 6 stictches and lost a tooth. There was no CCTV but there were witnesses, including a passer-by that didn't know anyone involved.
The police arrested the attacker who admitted the assault however he has only been given a caution, despite having 2 previous cautions already.
Is there any way for my friend to appeal this decision and get the police to press charges for ABH or assault? Failing this can a civil case be brought to claim compensation for his injuries(he requires very expensive dental work)?thanks.

[New Judge]

No, there is no right of appeal against the decision not to prosecute.

Yes, he can launch a civil action for compensation.

[tonywiltshire]

As NJ says your friend can take civil action and seek damages for assault as apart from it being a crime it is also a tort (civil wrong). You may be able to find a solicitor who will accept the case on a conditional fee agreement (no win no fee).