Transport for Wales has brought in a 54-year-old Class 37 hauled train. The locomotive, which was introduced in 1965, was last used on the network in 2005.
It is being used to provide extra capacity on the Rhymney Valley Line, while Transport for Wales awaits the arrival of more trains.
Amongst the first to drive them was the man who drove the very last service back in 2005.
Now 64, David “Dai” Beavan, learnt his trade on Class 37s when he joined the railway in the 1990s.