Both
Tayna and
Battery Megastore are excellent mail order sources for a wide range of battery types and brands and will certainly undercut Halfords.
I've had very good service from Taiwanese manufacturer Hankook and have them in both my Land Rover and Narrowboat. The latter set of five have already outlasted the previous set by three years.
Unless you use your Morgan every day, don't be tempted by exotic construction types and brands. The extra life you may get will not compensate the much greater initial cost. Remember batteries are consumables, better to have a new one of almost any brand than hanging on to an old one that refuses to die completely but will let you down eventually.
