It's mostly the post code. M22. Which is a joke, as this area is lovely compared to where I used to live, M15, which is a total gangland **** hole full of scumbags with no jobs who suck their teeth at you as you drive past, if they're not throwing something at your car that is or making gun gestures... But this new area is apparently less safe according to insurance!
I tried getting quotes pretending I live in the lowest risk postcode area, some lovely little place in Aberdeen, and I was getting quotes of £600 per year.