Class 37 locomotive 37175 stands at Cardiff Central while working the 2145 Canton Sidings-Canton sidings working on 4th April.  37219 is at the other end of the train.  It was due to visit various parts of the Valley Lines network overnight.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/126337928@N05">Jeremy Segrott</a> from Cardiff, Wales, UK
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/126337928@N05/33803669346/">Night time test train: 37175 at Cardiff Central</a>