that's insane. My first year of insurance when I was 17 costs me £1200 for the year, and that was with other named drivers in a 2007 Fiat Panda. Now I'm 24 and have 6 points and 2 car accidents behind me, yet my annual premium is still below half of what you were quoted.
What variables did you enter when you were looking?
Your age, expected mileage and voluntary excess are the big three. Some would say location, but I don't imagine Rhuddlan is a crime hotspot.
In your restoration project did you modify anything and declare it to the insurance comparison site? If so, that's your culprit most likely.