Reuben Ramble's Travels through the Counties of England
It's a tiny map set within scenes of Essex rural activities - it was written as an instructional book for children.
Displayed scale of 10 miles = 16mm, or 15.9 miles/inch; actual scale = 15.4 miles/inch, or 1:975,000.
It's Miller's 1810 map as last used in Darton's Miniature Atlas in 1822; Reuben Ramble's Travels was first published in 1825, and nothing had changed on the map by the 1845 re-issue - except for some very faint lines for railways from London to Colchester, and the fictitious Thames Haven line.