Star Alliance airlines offer Portland, Oregon PDX to London at round trip fares from $543 to $4593 for departures in April and May 2017. Published fares on Air Canada start at $588 and United at $593. Lower Star Alliance flights with ticket prices down to $543 are found on Momondo.com.
Delta/SkyTeam Alliance and Virgin Atlantic tickets start at $603 round trip for this route.
Departure Dates: April 6 – May 10 (similar dates to Seattle to Zurich, Switzerland deal today).
Air Canada Portland PDX – Vancouver YVR – London LHR – YVR – LHR
Delta Airlines Portland PDX – New York JFK – London LHR – Minneapolis MSP – Portland PDX
Momondo.com meta-search finds tickets priced at $543 round trip with Air Canada and United.