Gouge? I did it...it was crowded as hell. My captain took a bus. He arrived rested and ready for a pint. I was on my feet for 1.5 hours jammed up against the door of the train hoping it wouldn't fly open at 50 mph. I arrived ready for bed.
I love trains...on the continent. They are a bit crowded for my taste in England. Maybe you can get a 1st class ticket...I'm not sure.
I took the Heathrow shuttle to Kings Cross. Total time was 2.5 hours.
Again...I'm not senior enough to hold this regularly...I'm sure we got some MD11 gurus who can steer you in the right direction.