NCB ex GWR 0-6-0PT No 10 with train of coal empties at Percy Main colliery in the 1950s. This was former GWR 719 ex Barry Railway No 99 rebuilt by Swindon into the form shown here and bought by Harton Main colliery in 1934.
Comparing to the other photo of it here, it appears that here it is arriving from the colliery and then it will propel its wooden hoppers down the track to the right, controlled by the right hand pair of signals on the gantry.

Photo: W.J. Verden Anderson / Rail Archive Stephenson