By 1935, Pearsall had become a portrait painter but became lost in London while using the latest map she could find, which was 17 years old. This stimulated her to produce a new map to cover the rapidly expanding area of London, including places of interest such as museums, bus routes etc. Pearsall claimed that the work involved walking 3,000 miles to check the names of the 23,000 streets of London, waking up at 5am every day, and not going to bed until after an 18-hour working day. In her autobiography she points to one novelty: "House numbers along main roads; I've walked them from start to finish; you won't find them on any other London map." It is often claimed to be the first indexed London street map, but this claim is easily refuted by reference to Bartholomew's Reference Atlas of London and Suburbs, which was published and widely available from 1908 onwards. The first Pearsall A-Z claimed on its front cover to include "9,000 more [streets] than any similar atlas index", but in fact it had almost the same number of streets as the Bartholomew's version. The map was drawn using the 72 6" Ordnance Survey maps for London dating from 1919 by her father's cartographer, Mr Fountain, updated by visits to the LCC planning offices. In 1936, when her map was complete, she printed 10,000 copies and began contacting bookstores who might sell it. She tried
Hatchards in Piccadilly,
Selfridges, where they would not see her without an appointment, and
Foyles. None of them would take it. Next she went to
W H Smith where, after being snubbed for days by an office junior, she received an order for 1,250 copies, which she delivered using a hand barrow borrowed from the pub next door. They sold well and within weeks she was taking regular orders to every main railway station in London.
F. W. Woolworth took a few thousand copies too. By 1938 the London A-Z was well-established. Until her father's death in 1958, all copies included the words "Produced under the direction of Alexander Gross, F.R.G.S."; he was not actually involved but it was hoped that he would find the acknowledgement useful. In 1945, returning from a trip to Amsterdam where they were printing a new edition of the London map to get round shortages of paper in England, she was involved in a plane crash which left her with permanent scars. ==Later years==