I'm not a fan of advertising liveries unless they're done well and don't detract from the appearance of the locomotive or unit. 43.144 with its Building A Greater West branding doesn't make the grade in my opinion.
The power car was working 1L38, the 07:58 from Swansea to Paddington, through Sonning Cutting on 21 April 2015, assisted by 43.025 at the rear.
PHOTO DATA FOR IMAGE 15-D-0771
camera : Nikon D600
lens : 28-70mm f/2.8
focal length : 60.0 (60mm 35mm eq)
shutter : 1/1000 sec
aperture : f/9.0
ISO : 400 ISO
original : Digital: 24MP NEF
SUBJECT DATA
Loco / Unit : 43.144, 43.025
Train : 1L38, 07:58 Swansea - London Paddington passenger