it is indeed Darra, so well done br30453.
Over to you, br30453.
As I don't seem to be able to upload an image I declare open floor.
I guess it might be the Murwillumbah line "somewhere".
As to exactly where, I will have a WSITD at Dunbible?
This guess is a wild one, and depends on whether someone had access to colour film (Kodachrome, most likely) and the appropriate camera 70-odd yrs ago.
If that truly was the case, perhaps we're looking at Teven on the Ballina branch - bearing in mind that the line opened 25/8/1930, and that all (regular) pax services ceased nearly 13yrs later on 16/4/1943. Services weren't totally suspended until 11/6/1948 due to landslides, so if this train was where it was (Teven?) in the intervening 5yrs, it might have been a gunzel special, run by the organisation that was the ARHS' ancestor.
Thanks, as ever, to Mr. Bozier and Rolfeworld for the Ballina line info 8)
Not the Ballina line as that closed before 5910 entered preservation service.