In 2005, as a member of Combat 18, Quinn was charged with distributing copies of The Longest Hatred: An Examination of Anti-gentilism, a book effectively banned when Lady Jane Birdwood had been convicted in 1991 for distributing it.

He pleaded guilty to possession of racist material and was given a suspended sentence, although attempts to prove links to the Racial Volunteer Force were not pursued.

In September 2008, Quinn appeared before St Albans Crown Court on a charge of racially aggravated public disorder. The charge related to an incident in South Oxhey on 1 December 2007 after he had abused ethnic minority passers-by from a British First Party table that he had set up in the area.

The jury failed to agree on a verdict, but he was convicted and given a six-month suspended prison sentence at a retrial in St Albans Crown Court in April 2009.