Let's face it, just about every pilot coming off the Pond in the early morning of every day into Heathrow or Gatwick is knackered (I speak from long experience). You only have to listen to their voices on the radio.
Are we about to get into a situation whereby pilots are about to start calling Pan in order to get out of the Lambourne hold out of sequence?
If so, how are they ever going to be able to prove that they were more knackered than the others ahead of them?
I doubt that this idea is going to catch on but it would be very interesting if it did.