The Brecon Forest Tramroad was the brainchild of John Christie. His ultimate plan was to link the collieries in the Onllwyn area to limestone quarries around Penwyllt, and to carry lime northwards as far as Sennybridge to improve the land in the upper Usk valley. With limekilns at Sennybridge as well, some coal and limestone traffic made the journey northwards to the end of the line as well as the burnt lime. The first part of the line was short-lived, running from high in the hills at Pwll Byfre to Sennybridge, and was abandoned quickly when no coal deposits were found in the area. Geological knowledge was pretty rudimentary at the time! When the rural market for coal and lime proved to be limited, the line was extended southwards to the Swansea Canal which enabled a more profitable line in coal exports to be pursued. Even so, Christie was declared bankrupt in 1827. Joseph Claypon took over the running of the BFT, and built a further extension southwards to Gurnos. The line continued to carry coal to the canal and to new iron furnaces in the area, along with limestone for use in the blast furnaces. The line continued to function until 1863 when the Neath to Brecon Railway was opened.