I do love finding these lesser known parts of infrastructure
The way it was, check out some of these too
A selection of old maps on SABRE http://www.sabre-roads.org.uk/maps/
Side by side maps, the original course of the A406 around the Ace Cafe, courtesy of Sir Amos Ben http://maps.nls.uk/geo/explore/sidebyside.cfm#zoom=17&lat=51.5419&lon=-0.2777&layers=10&right=BingHyb
Many interesting roads and photographs on Mapco http://mapco.net/
One of my earliest memories of a road trip was when my father took us on a fishing holiday to Broxbourne c1962/3. He drove us by way of a circular route driving along the A406 from Beacontree Avenue as it was back then. Now a favourite of the dog walking fraternity. http://roadsnomore.tumblr.com/old-a406