Thurles was built in 1934 as works number 12475 and was assigned to Thurles where it spent most of its working life shunting. In the late 1950s it also spent time as a static boiler used to power machinery within the refinery.
The locomotive was withdrawn from service in 1962 after which it languished at the Thurles factory until it was bought along with two other locomotives (No 2 Thurles and No 3 Mallow) from the original nine. The purchase was made by a Dublin metal dealer on behalf of a private owner who wished to eventually operate them in England.
The three locomotives were moved by rail to Dalkey but the siding on which they were stored was later required for the DART electrification project. The CIÉ then agreed that the locomotives could be stored in a disused bus facility at Broadstone in Dublin but this meant that the locomotives would have to be transported by road to their new home. In order to pay for the transport costs one of the locomotives was sold to a scrapyard in 1977 and it was scrapped the following year.
The two remaining engines ended up at the site of Ballynahinch Junction in County Down in 1978. It was at this point that the owner of the locomotives realised they were the wrong gauge for an English railway. The locomotives remained at Ballynahinch Junction until 1987.
The recently formed Downpatrick & County Down Railway (DCDR) purchased the two locomotives and moved them to Downpatrick.
After many years of restoration, which included boiler work at the Railway Preservation Society of Ireland (RPSI) base at Whitehead, No 1 finally returned to traffic in 2012 at the DCDR.