Someone directed me to http://www.naval-history.net/xDKCasAlpha1939-45Br.htm where I found BURKE, Dominic, Marine, PO/X 107053, RN Beach Battalion, 14 September 1941, died - this maybe my ancestor. Equally this might be him -
BURKE, Edward, Ordinary Seaman, RNVR, D/MD/X 3139, Sultan, 16 February 1942, Singapore evacuation, MPK
Interesting thing here:http://www.combinedops.com/Elba - Op Brassard.htm
Again, it calls them Beach Commandos.
It also mentions people falsifying birth certificates . The subject was mentioned by someone on here recently.
If you go to the link on my above post (#2), and click one of the links to the National Archive, it refers to them RN Commandos.