It seems inconceivable that FGW were running 2-car DMUs on Oxford - Paddington services before electrification but this wasn't the only example seen. 165.125 was working 2P40, the 09:37 from Oxford, into Sonning Cutting on 23 May 2016, when it was overtaken by 43.145 and 43.036 on 1L38, the 07:58 from Swansea.
PHOTO DATA FOR IMAGE 16-D-2201
camera : Nikon D610
lens : 70-200mm f/2.8
focal length : 180.0 mm
shutter : 1/800 sec
aperture : f/11.0
ISO : 500 ISO
original : Digital: 24MP NEF
SUBJECT DATA
Loco / Unit : 43.145, 43.036
Train : 1L38, 07:58 Swansea - London Paddington passenger