I will have been with Metronet for 2 years in a couple of weeks time. The service just keeps getting cheaper! I am also on 1 Meg so will now only have to pay £13.75 a month as I rarely go over 2 Gig.
Just to add, you only pay 0.235p per MB over your included usage allowance, unlike other providers who charge in blocks. Once you reach 7535 MB the cost cap (not usage cap) kicks in.