LNER Observation car No 1729 on the rear of the down 'Coronation' near Ranskill hauled by A4 No 2512 Silver Fox in 1938. Note: this image as been marketed and reproduced numerous times as Claypole but it is Ranskill.
Note the double tail lamps. I know two on top of each other was a Slip Coach but have never seen two like this, but apparantly most of the pics of the rear of the Coronation in LNER days show the twin lamps - so must have been a special regulation .

Photo: Colling Turner/Rail Archive Stephenson