A few weeks ago I saw something interesting with a TPE 802 that I got between Leeds and Durham (on a service to Newcastle). It was in diesel mode at Leeds when I got on it as expected, switched to electric at York, again as expected, but then when I got off at Durham I turned around and saw the pantograph going down, just as the engine turned on, and then it left Durham in diesel mode, despite the rest of the way to Newcastle still being electric, not sure why this happened as it had been electric York to Durham, and it wouldn't have been taking the Sunderland divert or anything as that's at Northallerton.