RE have launched a series of flights between Dublin and Gloucester for the Chelteham races next March, usually a huge Irish event. The routes are on sale on their website but no ads that I have seen yet.
Arran have been to GLO on charter services so ATR seems capable - the April 2008 photo archive in the "enthusiast" site linked from the airport website has photos of three ATR72s on the GLO apron, presumably some rugby event?