Just wondered as I am currently bleeding my brakes/clutch (again) and can't see anything obvious up top and don't want to start stripping bits off for access if there's no point.

All in the search for a good firm pedal.

That looks like the stub of a brake line that's been cut not a bleed nipple.

It's dark out so I'll get the torch and inspection mirror out and see what's to see but I'm pretty sure I've looked all around and if I've missed it I've no idea how I'll get to it!

Nope, nada, zip, zilch, there's no bleed nipple on the master cylinder that I can see.

The 'nipple' you refer to in the picture IS a brake line.

Odd... there's no mention of it in the Haynes workshop manual either.