in that case
www.travelocity.co.uk shows fares from £224pounds which is about 400US$ dollars return on American Airlines from Boston to London as follows<<
Total price for this trip: £224.20
1 Review the flight details
Fri 25-Mar-05
Boston (BOS)
Depart 09:00
Terminal B to London (LHR)
Arrive 20:20
Terminal 3 3267 mile(s)
(5258 km)
Duration: 6hr 20min
Flight: 156
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Economy/Coach Class, Breakfast, Boeing 777
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Total distance: 3267 mile(s) (5258 km)
Total duration: 6hr 20min
Fri 1-Apr-05
London (LHR)
Depart 18:05
Terminal 3 to Boston (BOS)
Arrive 19:15
Terminal E 3267 mile(s)
(5258 km)
Duration: 7hr 10min
Flight: 155
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give them a try.