I'll do some more investigating today, Neil.
I was relieved to get it started without too much fiddling, so took it for a run to get everything warmed up - it was a lovely afternoon - and it was getting dark when I got home!
I'll do some cleaning around the battery and starter and see what I find.
(I used to get the dreaded 'K click' on my last Caterham until I applied a fix. It was a bit easier to bumpstart the Caterham singlehanded!)