The Vale of Rheidol Railway in Mid Wales has completed the conversion from coal to oil firing of 2-6-2T steam locomotive No.9 Prince of Wales.

Its first day back in traffic was Thursday, 30th April, which was fortuitous, as the previous day the railway had been forced to use diesel traction due to dry, windy conditions and the risk of significant local wildfires. Conversion to oil firing was precipitated by prolonged dry weather in 2025, with its attendant risk of lineside fires, leading to over 30 trains being cancelled and a complete weekend closure.

Oil firing will provide operational resilience by enabling steam services to continue operating whenever coal firing is an unacceptable risk.

This is not the first time that the Vale of Rheidol has tried oil firing. Oil-fired locomotives operated on the line in 1978, in response to the dry summer of 1976, but in 2011, the line reverted to coal in a move to prioritise authenticity and the visitor experience.

Changing conditions have since forced a reassessment, both by the closure of the coal mine at Ffos-y-fran and an increasing reliance on imported coal. The cumulative effect has seen higher costs and reduced fuel quality, with each round trip from Aberystwyth to Devil’s Bridge now requiring up to 30% more coal. Accompanying the increased costs has been an increased fire risk, even by using modern spark-arresting and ashpan mitigation systems.

The conversion of Prince of Wales has been designed so that it can be readily converted back to coal, with the original coal-fired configuration retained. The oil-firing equipment has been installed in such a way that the locomotive can be converted back to coal within about one week.

Fuel costs were a key consideration in the decision to convert to oil, with the cost of coal around £125 per train, compared with oil costing approximately £240–£300 per train before the outbreak of the Iran War.

In a further move to have an additional non-spark-emitting locomotive available, the railway is currently overhauling Bagnall 0-6-0 diesel locomotive No. 3124.

In 2023, the North Yorkshire Moors Railway announced that WD 2-10-0 Dame Vera Lynn was to be converted to burn ‘liquid’ fuels, including heavy oil and recycled cooking oil, and in 2024, the railway converted No. 2253 Omaha from coal to oil-fired

”Following the difficulties we experienced in 2025, it became clear that we needed greater flexibility in how we operate. Oil firing allows us to significantly reduce the risk of lineside fires while maintaining a steam-hauled service. This gives us genuine operational choice, and we can respond to weather conditions and fuel markets, rather than being constrained by them.”

Llyr ap Iolo, Vale of Rheidol CEO and Chief Engineer