Invaluable information. Thanks chaps!
I was completely unable to read the letters in the middle, but you are right, now that you mention it they definitely are QOH.

Indeed, I knew my grandfather was or went on to be in a cavalry regiment, so this fits. I didn't know that he was one of "Churchill's Own" though. Interesting stuff.
I'd just like to figure out if this was before or after the war.
According to the link shared above, the "Regiment saw extensive action during the Second World War in Greece", which is where my grandfather was captured and became a POW (before escaping).
Perhaps he was already in the regiment at that time...
Anyway, thanks again. Much appreciated.