The creation of writer and painter Phyllis Pearsall (1906–96), who got lost in London in 1935 while using a 20-year-old street map, the most up to date that was then available. Enlisting the services of James Duncan, a draughtsman who worked for her cartographer father, and setting up her own office in a bedsit in horseferry road, she spent more than a year walking the streets of the capital, covering 3,000 miles on foot, identifying and locating 23,000 streets, roads, squares, avenues, alleyways and cul-de-sacs, and creating her own map.

Unable to find a publisher willing to invest in the project, Mrs Pearsall formed the Geographers’ Map Company and produced the first edition herself in 1936, paying for the initial print run of 10,000 copies and delivering the first batch to W.H. Smith in a wheelbarrow. It was an instant success and has dominated the UK market ever since. Seventy years on, A-Z Street Maps are still produced by the company, ownership of which its founder transferred to a trust for the benefit of its employees in 1966, and which was renamed the Geographers’ A-Z Map Company Ltd in 1972.

Mrs Pearsall remained involved with its operations right up to her death at the age of 89. The number of streets listed in the London A-Z rose from 23,000 in the 1st edition to nearly 70,000 by the 5th edition (2004).

The commonest names are High Street and Station Approach (with 52 entries each), closely followed by Station Road (49), Park Road (46) and The Drive (40), while Victoria Road (37) narrowly beats Albert Road (32). The A–Z formula has since been repeated in street maps of many British cities. The company relocated from Gray’s Inn Road to Sevenoaks in 1962, before moving to its present headquarters in Borough Green, Kent, in 1991. The fruits of Mrs Pearsall’s labours are now available on CD-ROM for computers and direct to mobile phone screens and electronic personal organizers.

Excerpted from The London Encyclopaedia by kind permission of the Publishers, Pan MacMillan.

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