The Atlas was first published in 1837 (Essex is dated 1835), and then several times to 1871 (or later), as Hobson's Fox Hunting Atlas (1850 to 1880), as Walker's Fox Hunting Atlas (up to 1895) and as Lett's Popular Atlas (1884 & 87). The maps were also published separately, dissected on cloth and folded up between boards - as in this case.
Hundreds are referenced to a table, plus listing parliamentary boroughs, places of election and polling places. Hundreds have broad edge-colouring and are excessively colour washed, with Harwich & Maldon Boroughs red-lined and Colchester dark green lined. Four Polling Places in North, 6 in the South. Divisions very thickly edge-coloured. Major roads have a thicker line on one side; all roads uncoloured.
Scale correct at 1+12 miles = 83mm, or 3.9 miles/inch, ie 1:250,000.
Black quads to Bishops Stortford and to Chelmsford, but beyond those pecked black line all way towards Cambridge and towards Norwich; red over whole length. Also has Blackwall Rail, and the Romford - Thames Haven Docks (named), both red on pecked black.
I estimate its selling date as being c.1840 as no lines authorised after 1839 have been added.
Under the cartouche is "By J & C Walker", but along the bottom is "Published by Longman, Orme, Rees & Co, Paternoster Row, London, July 1st 1840".
Many J&C Walker maps are shown on the Walker's Map Publisher page.