I think that you may well find that some of these 'compare' companies are more involved than they appear to be.
A company called BSL of Peterborough seem to represent quite a number of well known insurance companies,so it might pay to check this before completing the transaction. They even issue annual renewals or initial claims, and have direct telephone numbers that appear to be a direct contact to the insurance company that you are using?.
One of our vehicles was due for insurance renewal the other day. Checking out some of the 'compare' websites, I was being quoted by a couple of company's that I had never heard about before. As an example, I have heard about Swift or Sheila but never Elephant (which seems a new kid on the block)?.