It's a wagon fitting.
These, being female, were the opposite of our own. If the last wagon of a train only had this bracket, a domestic lamp bracket could be inserted to make it into a male.
Coaching vehicles always had two brackets to allow lamps to be attached from a platform. My Ferryvan, with its through steam and E.T.H., was capable of being formed in a passenger train and thus had four lamp brackets at each end.
Best wishes, Colin
I was delighted to see Mike's excellent 1962 photos of Chelfham Viaduct. I am an L&B enthusiast - but Mike knows that. I attach a couple of photos which I think compliment those of Mike.
The B&W shot taken from the trackbed & looking along the viaduct was taken on 24th August 1966 when I walked from Barnstaple to the viaduct. It shows that most of the parapet walls had been removed to guard against brickwork decay & wall collapse. Of course there were quite high metal fences at each end to discourage access. I think I must have clambered up one to take this photo - it seems to be from quite a high vantage point! The prominent building at the far end was built as the Chelfham station master's house - a remarkably grand house for such a small station. Now named 'Distant Point' it is owned by a consortium of L&B Trust members & operates as a time-share. The station itself is at the far end of the viaduct. It is owned by the L&B Trust together with a 350yd length of trackbed northwards. Below the viaduct are buildings of Chelham Mill Special School which was closed in 2015. The site, disused since then, is currently up for sale but the buildings are in poor condition. Supporters of the L&B are considering whether it would be worth buying. It could provide parking for Chelfham station, volunteer accomodation, a museum, holiday lets, & various other amenities & visitor attractions.
The colour photo dates from 9th May 2015 and remarkably is an almost exact replica of one of Mike's 1962 photos. What is significant is that it shows the parapet walls have been rebuilt to their proper height. This was done as part of a major refurbishment carried out in 2000 by British Rail Property Board which included the installation of a heavy-duty water-proof membrane below the ballast; this will protect the structure & is robust enough to allow the viaduct to carry trains again. The installation of this membrane was financed by the L&B Trust. The viaduct is currently owned by the Highways Agency - successor to BRPB.