Shahpor, this increase would drive me mad, this is quite a lot, from £250 to £850!!! On what base?
And who knows if number of accidents are higher, I think insurance just makes stuff up like this!
When I moved within Glasgow, a few years ago, to a quieter area, closer to Primary school, more respectable area my premium went up as well something like by £100, when I asked insurance why the answer was - there was more car theft reported in that area! I am still staying at the same address.