Montagu's Road Map of the British Isles
Published by The Car Illustrated Ltd, 168 Piccadilly. This magazine had been founded in 1902 by JS Montagu (as in Beaulieu and the Montagu Motor Museum).
Covers East Anglia and Essex, being sheet number 4 of 11 that covered England & Wales at the quarter inch scale.
More details on Motoring maps are on the Publisher's page.
Displayed scale of 10 miles = 65mm, or 3.9 miles/inch, ie 1:250,000.
Legend has First class and Other roads, shown by thick and thin red lines; also shows gradients over 1 in 12 and "Dangerous Bends".
No print codes; no Tollesbury or Thaxted branches (opened 1904/07 & 1913 respectively), but from internet searches the road maps were published in 1910.