The Stratford sub Castle village local history group have written elsewhere on this website  of the historical significance of William Mudge and Old Sarum in the genesis of the Ordnance Survey. It was the threat of a French invasion that prompted him to come to Old Sarum and commence mapping the South of England in 1794. Countries do not publish up to date detailed maps when fearing invasion lest enemy agents obtain them. Napoleon's forces at sea were always far weaker than on land and the threat of invasion had receded well before Waterloo in 1815. Whilst there are earlier maps from other cartographers this is the first Ordnance Survey map of the area, published in 1817.
The Ordnance Survey has had four homes, the Tower of London till the mid-19th C then London Road, Maybush (1969 to 2011) and its current site Adanac Park all at Southampton. The engraving of this map was done in the drawing room at the Tower of London under the direction of Colonel Mudge by Benjamin Baker and assistants and the writing was by Ebenezer Bourne. The gun marking the end of Mudge’s baseline at Old Sarum is recorded on this and every subsequent Ordnance Survey map. The gun is still there next to a monument to Mudge.
The Old Sarum public house appears and the village of Ford is known as Winterbourne Ford. Bishopdown is Bishop’s Down. Salterton is Salterston. Just south of it is a hamlet known as Newtown. North of Salterton is Netton originally called Newtown. On the Bath Rd is South Newton. Camp Down by the Devizes Road already has the epithet of Old Camp Down. The Woodfords used to be Great (now Upper) and Little or Nether (now Middle and Lower) but have on this map acquired they names as used today. Hurdcott is Hurcot, Gomeldon is Gumbledon, Figsbury Ring is Clorus’s Camp.
Source is National Library of Australia. https://nla.gov.au/nla.obj-231918578/view
Details Creator Great Britain. Ordnance Survey Title [Old series Ordnance Survey maps of England and Wales] / engraved at the Drawing Room in the Tower ... by Benjn. Baker & Assistants; printed by Ramshaw. Call Number MAP RM 2734
Created/Published London : Published by Lt. Col. Mudge, Tower [and later] by Lieu M. Colonel Colby of the Royal Engineers; Sold by Jas. Gardner, Agent for the sale of the Ordnance maps, 163 Regent St., April 18th 1805-[1880?] Edition 1st edition. Catalogue Persistent Identifier https://nla.gov.au/nla.cat-vn1675181 Edition Out of Copyright.
APA Citation Great Britain. Ordnance Survey. & Mudge, William. & Colby, Thomas Frederick. & Baker, Benjamin. & Ramshaw. & Gardner, Jas. (1805). [Old series Ordnance Survey maps of England and Wales]. http://nla.gov.au/nla.obj-231917049