Thanks for your comments.
I'd made a print of this image & had noticed that it was intriguing upside down, but the novelty does wear off.
This one is another example of me not being entirely switched on to outdoor photography: It was taken over a year ago & I hadn't thought anything of it until I noticed it when going through my Lightroom catalogue a couple of weeks ago. ( I was probably deleting stuff, so it had a narrow escape ).
Graeme