Quote:
So who does fly direct to Logan from Heathrow? They would also need Logan - LA and LA - Heathrow routes for it to make sense to switch airline.

Well, all I do for these things is ask http://www.ebookers.com -- which says Virgin, BA, and American Airlines fly LHR-BOS. Ebookers' seat pitch guide is handy too. FWIW I had a very nice cup of tea on an American Airlines flight once. Unfortunately Ebookers won't tell you about flights that don't involve the UK (such as BOS-LAX) -- though this may be changing.

Peter