AirHint found the following cheapest one-way flights from Seattle (SEA) to London (LHR) in April 2026 (see full year).
One-Way flights
| 18 Apr | Icelandair | ||
| 21 Apr | Icelandair | ||
| 22 Apr | Icelandair | ||
| 07 Apr | Icelandair | ||
| 06 Apr | Icelandair | ||
| 04 Apr | Lufthansa | ||
| 27 Apr | Air Canada | ||
| 29 Apr | Air Canada | ||
| 21 Apr | KLM | direct | |
| 22 Apr | KLM | direct |
Also check the deals for return flights from Seattle to London in April.
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