PM listeners' sounds: Whirlpool

Dave, in Blackpool, sent this sound. He wrote: "I noticed this tiny whirlpool forming in a flooded ditch by the side of a country lane on the Fylde coast, Lancashire, Somewhere between Kirkham and Lytham St Anne's. I didn't really notice the sound at the time, It was only when I got home and had a listen through my headphones that the 'plughole' type sucking noise became apparent."