Churchill, Hastings Direct, Hagerty, Lancaster, and A-Plan are usually correctly priced. Best to take an online price to beat reference first where the first year is always competitive. And always shop around annually to keep the cost down.
As a ref', a friend have just insured his £60k 600+bhp V8 Jaguar F-Type R for ~£350 with 3k miles per annum. 57 years old, car garaged with Churchill. I pay £210 p.a. for my rebuilt Ninety Soft Top with an agreed value of £35k, again 57 years old, with 5k miles with Hagerty. We live in a low theft/AB1 area.