Mark is pretty much right on the button Bucky.
Advanced (absorbed) Glass Mat (AGM) batteries are about as good as it gets in the size/capacity we use. So it's really a cost/availability/warranty issue for what ever is available in England.
I still have the original battery after nearly 3 years and 10K miles... but I've always put it on a battery tender if it's going to sit for more than a few days.
Now that I've said this, it's almost a certainty that it will fail completely within the next 10 minutes.