The motorway that connects London to its most distant airport is also the main road to East Anglia, rolling across the hills of Essex and Cambridgeshire.
A gallery of images sent in by visitors to the site of original photos of motorways — including some impressive views of the M4 and M11 under construction.
It was the UK's only single-carriageway motorway, and twenty years ago it ceased to exist. This is the story of the strange fascination it held, and of my place in history.
The UK's first four-level interchange opened in 1966. Relive some of the wonder and excitement of this icon of the motorway era with the book published to mark its completion.