Approximately 67m of the lower section of wreck is reported to remain insitu after dispersal operations were undertaken in 1952-55. A porthole and a cherub log have been recovered and reported o the Receiver of Wreck. The full character and extent of survival of further archaeological remains is presently unknown.

Event and Historical Information:
The PLM 21 was built in 1921 by Sir Raylton Dixon & Co Ltd, Middlesbrough (yard number 622). Technical and configuration specifications are given as steel-hulled; 400ft long x 56ft breadth x 28ft 4in depth; 1 deck, 7 bulkheads; machinery aft; screw propulsion powered by 3 boilers linked to a quadruple expansion engine made by N E Marine Engineering Co Ltd, Newcastle. The PLM 21 was one of an order for eight similar vessels (i.e.. PLM. 20-27) which turned out to be the last vessels built at the Dixon yard which closed when PLM. 27 was launched in March 1922. At time of loss, the PLM 21 was owned by the Soc. Nationele d'Affretements, France, and was registered at Rouen. The collier had been requisitioned by the Admiralty to carry coal between Welsh ports and various naval dockyards. The PLM 21 went onshore on the Middle Channel Rocks on the 3 December 1944 and subsequently became a total loss. The funnel, bridge and superstructure were visible even at high water. A Notice to Mariners was issued (NM 2883/44). A buoy had been installed by 13 January 1945. In October 1947, HMS SEAGULL reported that only the derrick posts at the bow and stern were still visible. In August 1952, Trinity House reported that dispersal operations were to be undertaken and in February 1956 the wreck's warning buoy was removed.

Sources include:

Goddard, T, 1983, Pembrokeshire Shipwrecks, p.126
Larn and Larn Shipwreck Database 2002
Lloyd's Register Casualty Returns, Statistical Summary 1944, p.8
Receiver of Wreck Droits letter and printout June 2002, RCIM6/2/5/5
SS P. L. M. 21, Wreck Site EU
UK Hydrographic Office Wrecks and Obstructions Database. ? Crown Copyright and database rights. Reproduced by permission of the Controller of Her Majesty's Stationery Office and the UK Hydrographic Office (www.ukho.gov.uk).
 

Maritime Officer, RCAHMW, March 2008.

This record was enhanced in 2020 with funding from Lloyd's Register Foundation as part of the project ‘Making the Link: Lloyd's Register and the National Monuments Record of Wales’. Visit Lloyd’s Register Foundation Heritage and Education Centre for more resources.