Castlethorpe was a temporary terminus east of present junction 4.
Road scheme and chronology data is courtesy SABRE (where much of it was gathered by member Ross Spur), with additional data from the UK Motorway Archive, the Scottish Roads Archive and the Northern Ireland Roads Site.
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 second part of the story, where we learn why exactly the M4 gets narrower on the final approach to Europe’s biggest city.
The M4 into London was one of the UK's earliest and most ambitious motorway projects. It was bold, pioneering... and almost instantly regretted.
The humble West Yorkshire town of Halifax may well be the creator of the most adventurous urban road scheme in the country. It's astonishing, but what was built isn't even the half of it.
