Although I tend to put the battery on a trickle charger a day before a trip, I found that starting was becoming very sluggish. And the voltmeter was showing that during cranking the voltage was dropping dramatically. It's over 4 years since I had a new battery do decided it was time to get a new one.
First problem I had is that the connections I use are designed to fit a square terminal rather than the more usual post terminal. Also the battery tray is a bit smaller than the usual, so a standard 243mm length battery will not fit. I cannot go above 210mm.
The result was that I could not find a suitable replacement. On the other hand Europarts had a battery of the required size, but with post terminals. Also they had a 'winter discount' that reduced the cost from £99 down to £53.
A quick search on Amazon showed these, perfect adapters.
Once I relaised they were different sizes they fitted perfectly.