I'm with Adrian Flux too as they were pretty competitive and are easier to deal with when you have modifications.
They are a bit profiteering though in my humble opinion. A £30 admin fee for any changes is excessive. Also some years ago I had a BMW insured with them and took their breakdown cover, which included vehicle recovery. I had a not-at-fault accident and when I called their claims department they wanted me to pay £50 to have the car recovered. When I mentioned that I had breakdown they just fobbed me off and said it was a different department, and in the stress of the situation I just didn't want to deal with any more hassle and just paid it, which I'm sure is what they expect most people will do. They aren't really an insurance company they're a middle man, so if you have a claim don't be surprised to find yourself dealing with 5 different disconnected companies all handling parts of the claim.