Idol, I was referring to the influence on the future choice of passengers as my last post made clear. Not to some in flight debate conducted at the time.
Overstress, I'm quite familiar with the routes in question, thank you. And yes, the great circle route from SFO to LHR crosses the Atlantic a long way north, via Hudson bay and Greenland (although the winds of the day and ATC restrictions will modify the theoretical great circle route, of course). And by the time various London managers had been consulted, there was probably insufficient fuel to plan a more southerly route, perhaps via St Johns, as that would have been about 400 miles further - although much closer to suitable en-route alternates.
SFO to East US, transfer pax to another flight. That's what I conclude would have been the best overall compromise.