We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Stephen
saying something like:

Hello,

I posted this on he camping group but I've had no replies. perhaps
they are all on holiday?

I was advised (on uk diy) that a leisure battery might discharge if
left unused for some time and I was told that a solar charger would
top-up the charge and prevent this. What size solar panel would I
need? Does the output of the panel have to be a certain ration of the
capacity of the battery? If so, what's the magic formula?

BTW can you recommend a good make of leisure battery and any good
suppliers?

I've been using a cheapy 5W panel I got off ebay two years ago and it's
been topping up an 80Ah battery quite happily for most of that time.
Peak current from it is around 300mA during sunny days and dips to
almost buggerall on really horrible overcast winter days - 17mA or so.
Overall it works rather well and I'd buy another one as the need arose.