I suspect in this case it was a 153, but there has been at least one power car/TGS/power car train run in service in living memory: directly after the naming of 43198 "Oxfordshire 2007" at Oxford station, it ran together with a single trailer and a second power car on a special service to Didcot. Follow
this link and scroll down to the picture of the day for 09 Feb 2007!
Bet that went like the proverbial off a shovel...