165104 & 166203 pass Hinksey Yard on 24 September 2009 with the 15:37 Oxford to Paddington First Great Western service. In three car form there is very little to distinguish Class 165s & 166s, probably the most noticeable difference being the different shape of the roof ventilators. Another clear difference here is that virtually all the hopper window ventilators are open on the leading 165, while the 166 at the rear benefits from air conditioning and appears to have only one open window.