‘The Geographers’ Map Company was founded by Phyllis Parcel (1906-96) the daughter of Alexander Gross, in 1936 after she famously got lost going to a party. She is often wrongly credited with inventing the pocket London atlas. What she did is take an existing good idea, improving its usability and accuracy so that it became the best seller. It was also cheaper and lighter than most rival products, being printed in black and white on thin paper. The company continues to make a large range of excellent maps, atlases and electronic mapping products. In particular, the Greater London A-Z for iPad is an absolute joy to use’ (The Hunt House.com). This map post-dates 1948 when the London Passenger Transport Board was nationalised and became London Transport as named in the title cartouche. It appears to pre-date 1951 as there is no reference to the Festival of Britain and the South Bank. The Geographers’ Map Company did not publish any material during the Second World War and following it whilst London was reconstructed their material was printed in Amsterdam, until 1962 when they moved to Kent. ‘A list and brief history of London Atlases’, http://www.maps.thehunthouse.com.