AirHint found the following cheapest return flights from St. Louis (STL) to London (LHR) in December 2025 (see full year).

Return flights

02 Dec - 09 Dec	British Airways
01 Dec - 08 Dec	Air Canada
05 Dec - 12 Dec	British Airways
08 Dec - 15 Dec	British Airways
15 Dec - 15 Jan	Air France
11 Dec - 18 Dec	British Airways
04 Dec - 27 Dec	Air Canada
17 Dec - 24 Dec	British Airways
14 Dec - 21 Dec	British Airways
15 Dec - 02 Jan	Air Canada
23 Dec - 02 Jan	Air Canada
11 Dec - 02 Jan	Air Canada
22 Dec - 29 Dec	British Airways
26 Dec - 02 Jan	Iberia
20 Dec - 02 Jan	Air Canada

Also check the deals for one-way flights from St. Louis 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 St. Louis to London in December from $529

Return flights