AirHint found the following cheapest return flights from London (LCY) to Castries (SLU) in September 2025 (see full year).

Return flights

16 Sep - 24 Sep	Delta
20 Sep - 25 Sep	Delta
16 Sep - 23 Sep	Delta
05 Sep - 10 Sep	Delta
08 Sep - 17 Sep	Delta
05 Sep - 07 Oct	Delta
15 Sep - 22 Sep	Delta
05 Sep - 08 Sep	Delta
17 Sep - 25 Sep	Delta
17 Sep - 24 Sep	Delta
11 Sep - 25 Sep	Delta
22 Sep - 05 Oct	Delta
24 Sep - 01 Oct	Delta
24 Sep - 08 Oct	Delta
28 Sep - 12 Oct	KLM
28 Sep - 19 Oct	KLM
18 Sep - 12 Oct	Delta
30 Sep - 07 Oct	Delta
29 Sep - 20 Oct	Delta
30 Sep - 13 Oct	Delta

Also check the deals for one-way flights from London to Castries 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 London to Castries in September from $1125

Return flights