Letts Popular Maps (albeit now published by Mason & Payne)
It's the J&C Walker/Letts map, but now without the 1884 earthquakes and in with the large raft of constituency changes that arrived in 1885.
Hundreds referenced to a table, but uncoloured (and not edge-coloured), with only Colchester Borough shown as a different colour from the surrounding Division. No list of Polling Place, but the nine Divisions (West Ham being shown as a single Division with 2 MPs) are colour washed (not edge-coloured), with names overprinted on the map. Major roads have a thicker line on one side; all roads uncoloured.
Scale correct at 12 miles = 77.5mm, or 3.9 miles/inch, ie 1:245,000 (the same as the 1884 Letts map, ie a little larger than the engaved maps).
The line from Barking to Upminster to Laindon and to Pitsea has been drawn in rather weakly in red (opened 1885, 1886 & 1888 respectively, but all authorised 1882), but the line to Shoeburyness (also authorised 1882, and opened 1884) is not even shown as planned.
There is now no imprint at all beneath the cartouche, and across the base it's "Mason & Payne, 41 Cornhill, London EC". Letts had gone bankrupt and the maps were taken over and published by Mason & Payne.
The (identical) map was also sold dissected, mounted on cloth, inside green end boards, sold by "C Smith & Son - a Map & Globe Publisher, 63 Charing Cross, SW". I've assumed a sale date of 1887.
Many J&C Walker maps are shown on the Walker's Map Publisher page.