Surely some of the huge North American market in the London area must be drawing people from the Northwest or are they all going via Ams - though the volume on that route might suggest otherwise?
I've worked for Californian based companies for 24yrs now. I used to do the via LHR or AMS routes. Won't fly BA or KLM now if I can help it. So last month was via ATL to SJC. Way back via JFK as went to friends in Maryland for a few days.
Surely there is demand for a 3 - 5 times a week direct to SFO? See so many passengers who are going that way too.