Yes, I was on a non air con turbo which stopped just before Maidenhead. Fortunately by then it was not overcrowded so if you sat still and had enough battery life on your smartphone/tablet/e-reader of choice (or a good old fashioned book) it was just about bearable.
The driver did his best to keep us informed however with a very poor quality, low volume
PA▸ system coupled with the windows open and the engines clattering away it was very difficult to hear the information, however over the course of the hour or so I managed to get:
"sorry...delay...signal problems...all signals at red...power outage at slough"
some sort of UPS or backup power source would be a good idea