1Charlie. My handle is the R/T callsign I used for most of my working life, although I could have used "Heathrow Tower" instead.
I sat up front on a BA 747 landing at Heathrow. After landing the pilot was told to take a particular turn onto a taxiway. Captain said said "We'll take the first turn; it's quicker". I told him that he should do as he was told as he was not to know if the turn off he was about to take might have a problem. He readily accepted my point. ATC is the only agency which has the full picture of traffic, both aircraft and vehicles, on the ground and if a GA instruction is issued it would be folly to ignore it. Sorry, but that's my opinion put as poilitely as I can.