There is a GNR Atlantic on shed.Thanks to Pete Speller we now know the strange item in the field to the left of the signal is an early overhead electricity mast as shown on the 1951 OS map as 'Electricity Transmission Lines' and they would appear to go to ground at that point. The electricity line was paralleling the railway from Gt Wymondley. However on the 1966 map it is no longer shown so it may have been removed before then.