Of course it isn't ... but I've only hit the 3-hour mark twice. LHR ground arrangements sort of work (and sometimes, in T5, work extremely well) until something goes wrong. Then it seems to go downhill dramatically. In my view Heathrow/BA's contingency planning seems quite poor, and bad turns into worse very quickly.

The moment there is bad weather, BA should be able to swing into contingency mode, with a number of immediate priorities including getting passengers off aircraft. The pilot was extremely frustrated at being unable to muster any action (or, reading between the lines, much interest) from his ground contacts. The passengers were of course all getting quite itchy and saying things like "how hard is it to drive a bus over here and get us?". Even as a very frequent flyer I was getting sympathetic with this view after the first couple of hours.

True. But LHR T5 has plenty of bus gates, so it could well have been a solvable logistical problem. My guess is that somewhere in the chain there was someone not answering the phone, or someone off doing some other thing ... not a tightly-managed contingency operation.

Regardless, my point was about BA's level of interest in the end to end passenger journey, as measured by lack of acceptance of the issue in their customer service response -- especially if, as one poster above suggested, BA has responsibility for the ground arrangements at LHR too.