The Royal Automobile Club Touring Map of England & Wales
The cover says it's the Official Touring map, whereas across the top of the map itself it's the Official Motoring map.
As a half inch map is covers all of Essex, plus goes out into the neighbouring counties. Counties are edge-coloured, whilst first and second class roads are shown by thick and thin red lines. Dangerous hills are marked, plus distances along roads. Recommended Tourist Centres are marked with a blue star - but just 3 in Essex: Saffron Walden, Epping and Frinton-on-Sea.
More details on Motoring maps are on the Publisher's page.
Scale correct at 10 miles = 127.7mm, or 2.0 miles/inch, or 1:126,720.
On the railways, the Tollesbury Pier line is present (opened 1907), but the Thaxted branch is absent (opened 1913). This is sheet 15 (out of 20), and would be more accurately called "Essex" rather than "Chelmsford".
Copyright George Philip & Son, The London Geographical Institute. Being from Philips, the underlying map will probably have come from Bartholomews, but does not use the latter's contour tinting, leaving it a very crowded map.