I've been using Devitt for many years. Their prices are always very competitive.
I would probably give them a 5* rating but for the fact that their charges for making any policy change (address, bike, terms of cover, etc) are in my opinion extortionate.
I know that they are not alone in adopting this punitive pricing strategy. However, dropping the rating to 4* is my small (but ineffective) way of expressing my dislike of it.
Other than that, I can recommend them.
