It's of the Mumbles Train approaching Southend station on the way to Swansea. The view is from a long gone footbridge over the line.
About 45 years ago I took a black and white photo of this very same scene, and lent it to my barber, a Mr Bryn Parkyn - (also artist) of Killay, Swansea, who wanted to use it for a painting.
He used to hang and sell the paintings in his barbershop opposite St Hillary's Church in Killay.
I never had the photo back, but on past visits to Swansea I've seen souvenir postcards in W H Smith and other stores that are identical to my pic and I wonder ......