William TWIDDY married Susanna AVERY at Northam 24 Sep 1804. Rebecca TWIDDY was baptised at Ilfracombe 21 Sep 1806.
In 1851, William TWIDDY is still alive:
4 Hoe St. Cottages, Plymouth St Andrew HO107/1879 Folio 774 page 20
Thomas CREEK Head Marr 32 Waterman b. PLymouth
Sarah CREEK Wife Marr 34 b. Ilfracombe
William CREEK Son 10 b. Plymouth
WIlliam TWIDDY Grandfather Widower 78 Revenue Pensioner b. Ilfracombe
It's possible that John HARRIS died, because a Rebecca HARRIS married 5 Aug 1838 to a Richard PEARSE at Stoke Damerel Church.