The Glyn Valley Tramway (nprn 309457) was a narrow gauge railway constructed in 1872-3 to transport slate and granite from the Glyn Ceiriog quarries to the Shropshire Union Canal at Chirk. It took passengers from 1874, and was operated by gravity and horses until 1888 when it was converted to steam. This locomotive shed was probably built c1890 when improvements were being undertaken by the line engineer, Henry Dennis. The line closed in 1933 to passengers and in 1935 to freight, due to competition from road transport.
Old photographs show that the building originally had 2 ridge ventilators and a stack to the NW angle, but is otherwise little altered.

Source: Cadw Listed Buildings. ALH 30/01/2012