A Brush Type 4 running through Swindon on the Up Main.
The line nearest the left is the Down Goods which was removed to build the new platform 4, along with its signal, SN38, on the gantry. Of the three remaining signals, SN40, 42 and 44, the middle one, SN42, had its stencils replaced with three position light junction indicators in 1979 (so this photo must be before then). The signal had positions 1, 4 and 5, leading to the Down Main, Up & Down Goods and Down Kemble respectively. The numbers 4 and 5 indicators to the Up & Down Goods and Down Kemble were taken out of use in November 1992 when the crossover that is beneath the engine was taken out of use. The feathers were removed in July 1993, leaving the signal with only a number 1 junction indicator, that it retains today.
(Another similar photo that was with this one has evidence of being before 1976).