A former British National Party member has been fined for repeatedly punching a protester who vandalised a party poster in Aberdeen.
Steven Thomson, 42, was found guilty of assaulting Stefan Knust in March 2010.
Thomson, of Shetland, claimed he had been putting his victim under a citizen's arrest in Aberdeen.
Sheriff Malcolm Garden, at Aberdeen Sheriff Court, fined him £300 for what he said was a citizen's arrest that went too far.
Mr Knust, 21, said he was attacked on Great Northern Road.
Fiscal depute Victoria White argued Thomson had used "brutal and excessive force".
But defence solicitor Gail Goodfellow said the victim's account of the attack did not match up with his injuries.
Thomson said he would appeal as he was "disgusted" by the conviction.
The case against Thomson's son, Gregor, 21, of Aberdeen, was found not proven.
The father and son had denied the offence and claimed they had been guarding the poster after it was repeatedly targeted by vandals.