Yeah Esure won't quote the zed for me either. I'm with Bell. I'm guessing it may be down to location rather than your personal details. Not saying you live in a dodgy area but the postcode maybe gets lumped in with other areas?
Try Keith Michaels - they did a good deal for me when i first got the zed. Particular good for insuring imports.
http://www.keithmichaels.co.uk/