Well HIC get my vote, i've just changed over from Direct line as they wanted another £120 a year if i added coiloivers.
HIC covered my MK2 GTI8v on a classic policy and limited mileage and were much cheaper than anyone else. They also don't object to modifications ie brakes,exhaust, suspension etc.
Direct line wouldn't cover me if i added a stainless exhaust as they said it would increase the performance!!!