AirHint found the following cheapest return flights from Montreal (YUL) to London (LGW) in September 2025 (see full year).

Return flights

29 Sep - 07 Oct	Air Canada
14 Sep - 21 Sep	FrenchBee
30 Sep - 07 Oct	Porter Airlines (Canada) Ltd
05 Sep - 09 Sep	Air Transat
25 Sep - 08 Oct	TAP
29 Sep - 06 Oct	Porter Airlines (Canada) Ltd
24 Sep - 28 Sep	Air Canada
24 Sep - 20 Oct	Air Transat
28 Sep - 07 Oct	Air Transat
17 Sep - 30 Sep	FrenchBee
12 Sep - 14 Sep	FrenchBee
26 Sep - 09 Oct	Air Transat
29 Sep - 03 Oct	Air Transat
11 Sep - 03 Oct	Air Transat
15 Sep - 03 Oct	Air Transat
12 Sep - 30 Sep	FrenchBee
14 Sep - 19 Sep	Air Transat
12 Sep - 19 Sep	FrenchBee
17 Sep - 24 Sep	FrenchBee
10 Sep - 17 Sep	FrenchBee

Also check the deals for one-way flights from Montreal to London in September.

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 Montreal to London in September from $552

Return flights