Adding a second car on my insurance

[v8mustang]

Has anyone with 2 or more cars had them all on the same policy? Just bought a new car and changed the insurance over to it, with the intention of selling the old one. However, I'm now having second thoughts about getting rid as it's a big old estate and perfect for carrying crap, going camping and going to some dodgy parts of town, these are rare trips, maybe 1000 miles/year tops. My insurance told me I'd have to start a new policy with 0 years ncd and charge me £500+. Do classic car owners have separate policies just for going to shows etc ?
Thanks