Update: I managed to reduce the initial proposed insurance premium by £50. When I first complained they offered a £25 reduction. However, I decided to go online and it was even cheaper with the same insurance company! So overall, I've still had to pay a 38% increase, which I still think is way over the odds, but it's better than their original quote.
Moral of the story - always do a price comparison and always obtain an online quote from your current insurer because it may be cheaper than their initial offer for renewing with them.
++Grandson of New Limerick (Son of New Limerick cont)
