English British surname originating as a place name. There are several Westbury villages, parishes and even Manors across England that have given the name Westbury to people who take up residence in or come from those places.
An example of this is in Kent in the parish of Wateringbury, there was a Westbery manor, which burnt down in the early 1900's. A family of Westbery/Westbury derived there surname from living in the Manor in the 1300-1400's.
Further examples include the 1st Head Master of Eton, a William Westbury in the 1400's, who derived his name from the village of Westbury in Wiltshire.
Other Westburys have be known to derive surnames from Gloucester, Shropshire, and Somerset. Potential other counties include Bedfordshire. Well known locations for Westbury's are Wiltshire, Warwickshire, London, Gloucestershire, Oxfordshire.
By the 1500's with the introduction of parish records by Henry the 8th, it was necessary to record surnames. This led to it being established as a permanent surname. Over the centuries of being recorded by relgious offcials numerous variants have resulted.