William Devonshire Saul (1783-1855) was a radical philanthropist and geological collector. He began is career as a wine and brandy merchant, based at Aldersgate Street, London and used his wine importation profits to help build the Owenites' City Road Hall of Science and John Street Institution. An avid collector, built a large geological museum adjoining his house at 15 Aldersgate Street, which was open to working people. He was also interested in phrenology and became a member of the London Phrenological Society.
In 1850 and 1851 he presided at the John Street Institution over the celebrations of Robert Owen's seventy-ninth and eightieth birthdays, in Owen's presence. By then Saull was owner of Owen's town house and mortgagee of Rosehill, the estate at the centre of Owen's co-operative experiment at Harmony Hall in Hampshire.