AirHint found the following cheapest return flights from Washington (IAD) to London (LHR) in December 2026 (see full year).

Return flights

09 Dec - 14 Dec	TAP
01 Dec - 08 Dec	Aer Lingus
27 Dec - 03 Jan	SWISS
27 Dec - 02 Jan	SWISS
25 Dec - 02 Jan	SWISS
26 Dec - 03 Jan	SWISS
26 Dec - 02 Jan	SWISS
25 Dec - 01 Jan	TAP
10 Dec - 06 Jan	British Airways	direct
25 Dec - 01 Jan	Finnair	direct
26 Dec - 03 Jan	Finnair	direct
25 Dec - 02 Jan	Iberia	direct

Also check the deals for one-way flights from Washington to London in December.

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 Washington to London in December from 511€

Return flights