found on Strange Maps, http://strangemaps.wordpress.com/2009/10/18/417-as-it-might-have-been-hexagonal-london/  who found it in London as it Might Have Been

Leighton, a Fellow of the Society of Antiquaries, published a scheme to divide London in a number of hexagonals, specifically aimed at preventing overcharging by cab drivers.

“John Leighton suggested that the old borough boundaries should be altered to conform to a honeycomb pattern. Within a 5-mile radius of the General Post Office all the sprawling, differently sized boroughs were to become hexagonal-shaped areas, 2 miles across. There were 19 altogether with the City in the centre of the honeycomb. Each hexagonal borough would be identified by a letter, and the letter as well as a number would be painted or cut out of tin-plate to be visible by day and night on lampposts at every street corner.”

The proposal for a hexagonal London is described in London As It Might Have Been, a book by Felix Barber and Ralph Hyde, also detailing plans for a giant pyramid to house the remains five million dead Londoners, and a scheme to erect a structure in Wembley to dwarf the Eiffel Tower in Paris.

Leighton’s hexagonal plan obviously never came to fruition