For 22 years with my BGTV8 I used Peter Best Insurance because they were MGCC approved and the cheapest by far. In 2008 I simply transferred the cover to my Roadster and assumed that it would be competitive, Peter Best was included on the MSCC approved insurers list. I don't remember now how much that was. But here's the thing. At the 2009 Mog, Gott & Wynne had a stall, and so I enquired about cover, and it was around £100 cheaper than Peter Best. Not only that but the two guys were knowledgeable and helpful. I've stayed with G&W ever since and just renewed. 2005 Roadster + 2016 Plus 4 on 5k miles each came out at £699. I don't think £350 each is a bad deal.
PS, in the early days, G&W supplied a breakdown as to how the premium was calculated, and the agreed value was a big player in this.
DaveW '05 Red Roadster S1 '16 Yellow (Not the only) Narrow AR GDI Plus 4