Cheers bud.
Yeah the UK started using the L1A1 SLR around the mid 50's, I believe. The L1A1 is a derivative of the FN FAL, and was built under licence from FN. Even though both the SLR and FAL look the same, the L1A1 has a few different features compared to the FAL.
The UK version of the FAL then went on to be used by other countries like; Australia, Brunei, Canada, India, Jamaica, Kuwait, Malaysia, etc.
As for the watermark, it was added for two reasons. Firstly to emphasise the 'British' part, and secondly to try stopping it from being used without my consent. As I have had a lot of trouble with a few of my images being used on various websites without my knowledge. And one of those websites are the ones that charge you to download the image. took me nearly a year and legal action before they eventually removed it. Never did see any royalties from it either!
Which is why I always try to advise to people that post either high quality or artistic shots of their kit/rifles, to either water mark them with a logo or add 'such and such photography' somewhere in the shot where it can't be cropped out.