These locomotives are ex-tunnelling locos manufactured by Hunslet Barclay, Leeds. They have four wheels, are five metres (just over 16 feet) long and weigh in at twelve tons. Built for the mining industry, the locomotives are typical of compact low-speed high tractive effort narrow gauge diesels.
The Deutz air cooled engine is of the 912W type widely used underground, and throughout the construction and marine industries. It is a six cylinder in-line engine designed for high torque at low speed, rated at 63kW (84 hp), maximum revolutions about 2500 rpm.
The two locomotives were named Kathy and Emma by their previous owners. Kathy was the penultimate locomotive built at Jack Lane, Hunslet, Leeds. They last worked on the Jubilee Line Extension project, London, operated by a consortium of Balfour Beatty and Amec, although owned by Hunslet Barclay. When the extension project finished, they were sold along with several other similar locos.
Emma has been commissioned with air brakes, couplings and a basic cab to compliment Glaslyn on passenger duties.
Once Russell is rebuilt and funds are available, the intention is to overhaul Kathy and rebuild her with a WHR heritage image cab that fits the Railway's policy.