Mostyn John Armstrong (fl.1769-91) was the son of Andrew Armstrong, both were cartographers although only the son published any atlas. Their focus was on Scottish related material with the notable exception of three large scale county maps of Cambridgeshire, Lincolnshire and Norfolk. The work was first published in 1776. This is the 'third edition' of this work, the date on the title page is altered to 1 January 1777. However in this example the dedication to Thomas Pennant on the following page is reset and now dated 23 August 1783 indicating a late issue. The ensuing preliminary leaves on Post Stages are reset with the inclusion of an N.B. referring to the late Act requiring 1d. per mile duty to be paid for each horse. The previous advert within the text for 'An Actual Survey of the Great Post-Road between London and Dover' is removed. The ‘Alphabetical Index of the Post-Towns’ is similarly reset. The plates themselves are consistently updated. Provenance: private English collection. References: Carroll (1996) App. 14.iii; ESTC N36298; Fordham (1924) p. 31 not differentiating the two 1776 editions.