The Ordnance Survey Act 1841 (c.30) The Ordnance Survey Act 1841 (c.30) Changes not yet applied. Later legislation changes this provision in ways not yet written into the text below: Sch. 10 para. 40 repealed by Greater London Authority Act 1999 Sch. 34 Pt. 1 6Paragraph 6 The Ordnance Survey Act 1841 (c.30)