In the late 1960s, Harry Margary obtained a copy of the Andrews, Dury & Herbert map of the County of Kent and was investigating the possibility of producing a few copies of the map for friends. Being a perfectionist, it was important that such copies were of the highest quality. Word of this project spread and others let it be known that, if available, they would also like a copy. From this initial project, Harry Margary, a Senior Civil Scientific Engineer working for the Admiralty (but very much regarded himself as an inventor) found himself with a business on his hands that encompassed his interest in cartography.
Since then, he published facsimiles of many of the large scale county maps all to the same high quality, either on his own account or in conjunction with the Guildhall Library, the British Museum and the London Topographical Society, amongst others. As a departure from the standard facsimile, he published facsimiles of the Old Series Ordnance Survey series and six volumes of the A-Z series.
In addition to the County maps, he has published facsimiles of 17c playing cards and other individual and sets of prints.
Since August, 1998, when Harry Margary died, the publishing house has been run by his son, Giles de Margary and his wife Amanda. In 2000, the business was moved to London and then, in 2005, to its present address in Suffolk.