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.
The tale of how British traffic signing developed between the Second World War and the mid-1960s, bringing us from a system designed at the turn of the century to the signs we still use today.