What connects the death of Brian Jones, founding member of The Rolling Stones, and Winnie-the-Pooh ?

I believe he drowned at the house formerly owned by the creator of Winnie the Pooh

Exactly so : Alan Alexander Milne lived at Cotchford Farm, Hartfield , East Sussex from 1925. It was there that he wrote the stories of Winnie-the-Pooh [the name was hyphenated, like some treble-barrelled surname: it lost its hyphens when Disney bought the rights and recreated the stories].The stories are set in the area.

Brian Jones had literally bought the Farm when he did so figuratively in 1969,being found dead in the swimming pool there.