Pax B: It wasn't a 744, but an early 747 - 100 of (I think ) Pan Am in about '72 or '73. As told to me it came past the Camberley area heading for Heathrow at about 1200ft and dumping fuel!!
I was on duty when the very first Pan Am 747 departed Heathrow on its first day of operation in 1970 on a 'jolly' out to BCN and back so not much fuel etc. It's first call to London Control? 'I'm not going to make 4000 by Woodley'!!