A transformer weighing 123 tons is required for the power station at Blaenau Ffestioiog, filmed by the British Transport Film unit. Forget about health and safety!!. Footage of the Conway Valley line  showing a Class 20 1000hp loco hauling the cavalcade, with a 4F keeping behind as a mobile buffer unit in case the coupling failed on the transformer train!.

To finally move the transformer into it’s final resting place at the power station, it was moved on tracks that measured approximately 6ft 6 ins apart. This track is still there on site.  Not many places in this country to have broad gauge and narrow gauge within about 100 metres of each other.