Since 1996, three sections of a new A421 expressway have been built, progressively completing a fast route that serves to link Cambridge to Milton Keynes and Bedford to the wider world.
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 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.