AirHint found the following cheapest return flights from Portland (PDX) to London (LHR) in October 2025 (see full year).

Return flights

11 Oct - 15 Oct	Icelandair
28 Oct - 04 Nov	Icelandair
09 Oct - 01 Nov	Icelandair
22 Oct - 29 Oct	Icelandair
16 Oct - 31 Oct	Icelandair
07 Oct - 17 Oct	Air Canada
15 Oct - 22 Oct	British Airways	direct
06 Oct - 22 Oct	British Airways	direct
29 Oct - 05 Nov	British Airways	direct
21 Oct - 28 Oct	British Airways
07 Oct - 14 Oct	British Airways
19 Oct - 26 Oct	Air Canada
05 Oct - 25 Oct	Air Canada
31 Oct - 07 Nov	Air Canada
14 Oct - 08 Nov	Air Canada
31 Oct - 07 Nov	Aer Lingus	direct

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

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 October from $497

Return flights