The halt was established in 1965 to serve Plas Dduallt, a small Welsh Manor House (just below the railway) dating in part from the 15th century, and where Oliver Cromwell is said to have stayed during his campaign against the Royalists of North Wales.
Colonel Andrew Campbell bought the house in 1962 and undertook a complete restoration. Road access to Plas Dduallt is recent and during the 1960s the Colonel kept his own locomotive on a siding by the halt. He ran his own train to and from Tan-y-Bwlch under running powers granted by the Ffestiniog Railway.
The Colonel allowed the use of his outhouses for hostel accommodation for volunteers. He was a licensed explosives handler and as a volunteer he did much of the rock blasting required on the spiral section of the deviation and beyond. A slate seat has been erected at Dduallt in his memory.
Campbell's Platform (named in his honour) is a private halt available for use only by residents and visitors staying at Plas Dduallt. Intending passengers must check with the Ffestiniog Railway Company before embarking on their journey.
Plas Dduallt has been on Most Haunted in its 2008 series for paranormal investigations.
Between Campbell's platform and Tan-y-Bwlch is Coed-y-Bleiddiau cottage, a private residence that was built c1860 for the Ffestiniog Railway's Inspector of the Line. The cottage is over half a mile by steep footpath from the nearest road, and in the 1930s it was used as a holiday home by several families, including that of Kim Philby the Russian spy. This cottage also has its own private railway platform, which displays a name board. However, this is not available for public use, and the location features on the map in the Traveller's Guide, but not on the company web.
Butt, R. V. J. (1995). The Directory of Railway Stations: details every public and private passenger station, halt, platform and stopping place, past and present (1st ed.). Sparkford: Patrick Stephens Ltd. ISBN1-8526-0508-1. OCLC60251199.