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.
Hundreds are referenced to a table, plus listings parliamentary boroughs, places of election and polling places. Hundreds are colour washed (but not edge-coloured), with Colchester, Harwich & Maldon Boroughs all blue-lined. Six Polling Places in North, 7 in the South. Divisions thickly edge-coloured. Major roads have a thicker line on one side; all roads uncoloured.
The map always protruded into Longitude border to the west of Walthamstow, but now also protrudes southwards to the Thames. Places are now named in Kent - but no railway. Many places now added in Hertfordshire, both west of SW Essex and also in the notch north of Roydon up to Gt Chesterford.
Railways are shown by two pairs of thin black lines (making a "quad line"), that sometimes overlap (making just a "triple line"). These run from Bishopsgate St to Colchester (authorised 1836; opened 1843) but not beyond, and from West Ham to Bishops Stortford (1835; 1842), but again not beyond, plus Blackwall Rail (1837; 1840); these then have red lines drawn over them. In addition, there are free drawn red lines (ie no underlying lines) from Roydon to Hertford (1841; 1843), plus a red line over the faint pecked black line from Romford to Thames Haven Docks (authorised 1836, but never built). There is also a black pecked line from Colchester into Suffolk (1836 & 44; 1846) - "Railroad from London to Norwich".
Under the cartouche is "By J & C Walker", but along the bottom is "Published by Longman, Orme, Rees & Co, Paternoster Row, London, July 1st 1842". From the red lines, I estimate its selling date as being c.1843.
Scale correct at 1+12 miles = 82.5mm, or 3.9 miles/inch, ie 1:250,000.
Many J&C Walker maps are shown on the Walker's Map Publisher page.