AirHint found the following cheapest return flights from Kolkata (CCU) to London (LHR) in September 2025 (see full year).

Return flights

21 Sep - 02 Oct	Air India
23 Sep - 02 Oct	Air India
25 Sep - 02 Oct	Air India
20 Sep - 01 Oct	Air India
24 Sep - 09 Oct	Air India
24 Sep - 30 Sep	Air India
25 Sep - 30 Sep	Air India
25 Sep - 27 Oct	Air India
18 Sep - 09 Oct	Air India
30 Sep - 03 Oct	Air India
26 Sep - 06 Oct	Air India
26 Sep - 02 Oct	Air India
20 Sep - 28 Sep	Air India
17 Sep - 20 Sep	Air India
20 Sep - 27 Sep	Air India
15 Sep - 18 Sep	Air India
16 Sep - 21 Sep	Air India
14 Sep - 30 Sep	IndiGo
14 Sep - 21 Sep	Air India
10 Sep - 15 Sep	IndiGo

Also check the deals for one-way flights from Kolkata 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 Kolkata to London in September from 456€

Return flights