I saw this scene one October as I drove past the Belle Tout lighthose- there was this wirlwind of House Martins and Swallows swirling around the building- obviously using the thermals rising from the building, bringing up insects for them to stock up before setting across the channel on their migration to winter feeding grounds.
The original working sketch was donated to the St. Wilfrids Secret Art Sale in 2014 and ended up in the top 10% of sales in the auction.