This British Atlas
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. This example is from an atlas dated 1849.
Hundreds referenced to a table, plus listing parliamentary boroughs, places of election and polling places. Hundreds uncoloured, but 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 are uncoloured.
Still no railway in Kent (authorised 1837; opened 1849), and compass rose still in Hertfordshire.
Scale correct at 1+12 miles = 83mm, or 4.0 miles/inch; actual scale = 3.9 miles/inch, or 1:250,000.
The old red line from West Ham to Woolwich Reach has been replaced by black quad line from West Ham down to Plaistow Level, then swinging east to North Woolwich (opened 1850), all with red overlay.
The railway red line from Marks Tey to Sudbury is now over a black "quad line", and follows a better route (authorised 1846; opened 1849); Chapel to Halstead (1856; 1860) is also now red line over quad black. There are quad black lines (with red overlay) from Sudbury to Clare (1847; 1865), from Clare & Sudbury towards Bury St Edmonds (1847; 1865), and from Manningtree to Harwich (1847; 1854). The faint pecked black line from Romford to Thames Haven Docks has no red overlay.
"By J & C Walker", but along bottom "Published by Longman, Orme, Rees & Co, Paternoster Row, London." There is no date on the map, but the Atlas is dated 1849, and from the red lines I estimate it was also sold in 1849.
Many J&C Walker maps are shown on the Walker's Map Publisher page.