AirHint found the following cheapest return flights from Portland (PDX) to London (LHR) in March 2026 (see full year).

Return flights

24 Mar - 31 Mar	Icelandair
02 Mar - 09 Mar	Air Canada
25 Mar - 31 Mar	Iberia
29 Mar - 07 Apr	British Airways	direct
23 Mar - 31 Mar	Virgin Atlantic
25 Mar - 01 Apr	Finnair
03 Mar - 10 Mar	Delta
29 Mar - 06 Apr	Virgin Atlantic
16 Mar - 02 Apr	Delta
29 Mar - 17 Apr	Delta
26 Mar - 01 Apr	Icelandair
02 Mar - 09 Mar	British Airways	direct
25 Mar - 30 Mar	Iberia
24 Mar - 30 Mar	Iberia
29 Mar - 06 Apr	British Airways	direct
26 Mar - 02 Apr	Delta
29 Mar - 12 Apr	Delta
06 Mar - 09 Mar	British Airways	direct
22 Mar - 05 Apr	Delta
09 Mar - 16 Mar	Icelandair

Also check the deals for one-way flights from Portland to London in March.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Portland to London in March from 469€

Return flights