Mine is with Privilege - and I even rang them up to confirm that I had used the right category. I think it was "maisonette" in their case.
Think I found them via confused.com but it might have been CompareTheMarket.com. I've been with them 3 years now - even though I check their renewal premium (buildings and contents) each year, they still come out as amongst the cheapest.
It is sometimes difficult to find insurance as some of the insurance companies can't cope with the fact that there is no leasehold in Scotland and we jointly, with our downstairs neighbours, are responsible for the roof and foundations 
We were with LV= before - only moved from them because trying to insure bikes more expensive than £300 each made their quote prohibitive. Until then they'd been good value and dealt well with our claims (over about 10 years, 2 bikes and one water damage to our neighbours )
Dh calls our house a "horizontal semi": the 1st and attic floors (with entrance on the ground floor) of a Victorian stone villa.