Thanks for all the advise!
I went to Dave W's post which was most helpful and agree with him that most of the websites are pretty useless and even the Banner site appears to directs you to the wrong battery!
I've eventually gone for a Banner PowerBull 60 09, which is the correct size and has a CCA of 540. It definitely turns the engine over quicker!
Cost 75.99 incl. VAT.
