The Comprehensive Gazetteer of England & Wales
Brightly depicted Parliamentary Divisions, plus some hachuring for hills - which looks overstated in the south and positively Alpine in the north west (we do have more than in the south of Essex, but it's a rolling landscape, not fjord-like valleys).
Displayed scale of 8 miles = 36mm, or 5.7 miles/inch; actual scale = 5.4 miles/inch, or 1:345,000.
The railways shown include the Upminster to Romford line (opened 1893), but not the Forest Gate to Tottenham link (opened 1894). The Gazetteer was published in 1893.