When I flew into Heathrow on a BA B747 from DFW back in April, it was to a bus gate.I seem to recall either the pilot or co-pilot apologising for it and said it was due to the aircraft needing to be towed across to maintenance once the passengers had disembarked.
I did think why not tow it from a jetway gate, but I suppose it was a disembarkation only onto buses and it left a jetway free for aircraft on a 'proper turnaround' stop.
As I am a crutches user the CSD did ask if I wanted to wait for a hi-lift truck to ‘rescue’ me and someone else in a wheelchair but I took my chances slowly on the front stairs, straight onto a bus waiting for the remaining Club World passengers.
There was a line of BA buses so even the World-traveller pax should not have had to wait too long to get to the terminal.
BM