Thanks for that. On closer examination, they've also all got a rectangular dent to the side of the base that I assume is the mark left by the extractor?

(Perhaps I shall add them to my 'L4 collection' whch currently consists of an L4A1 magazine and an LMG oil can)

Very sadly this now means that I shall probably start looking at the bases of fired .303in and 7.62mm cases to see if they had the good fortune to give their all in a Bren.

Cheers,
Mark