Thank you, all, for your assistance.
I have removed the barrel - simple enough. However, I cannot remove the end cap/plug at the end of the pistol (or front of the cylinder, to look at it another way). It appears to be an extremely thin join and there is no means of inserting a screwdriver into any gap to prise it apart. Equally, there is no means of turning it or screwing it, to undo it.
Thus, completely stuck - and not as simple as doing up a shoelace!
How do I remove the end cap?! Clearly, it does not just spring out.
Rgds
A