The short line was built in 1848 by the Admiralty [at 7ft gauge] to transport rocks from the quarry at Holyhead Mountain to the breakwater. It was changed to standard gauge in 1911 but by the 1970s stone was no longer extracted from the quarry and the line had been lifted. The blocks were being imported from the Penrhyn Slate Quarry by road and the remainder of the track closed in 1980 with all operations being carried out by road vehicles.
This was not regarded as a Departmental Depot but the Departmental Locomotive was hired out to this location.
Facilities; A stone built 2TS dead ended shed with a slated gable-style roof, located at SH23528357, and a water tank were provided for the loco.
Locomotive Allocation & Duties;
ED6  [March 1966-September 1967]
01001 [June 1967-September 1979 (Stored OOU)]
01002 [June 1967-March 1981 (OOU from 1980)]

One of the two last-surviving Capital Stock Class 01 0-4-0 locos that ended their days at Holyhead Breakwater, No.01001 is seen inside the shed on July 23rd, 1974.                                   AM Clarke

No.01002 parked between duties on April 15th, 1979. By now it was the only one of the pair still operational.           Dave Plimmer