Stanborough Park was a temporary terminus part way between modern junctions 4 and 5.
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.
The M4 into London was one of the UK's earliest and most ambitious motorway projects. It was bold, pioneering... and almost instantly regretted.
An introduction to what I write, and why I write it, and where my strange new road sign simulator fits in to all this.
It was specially designed never to be noticed. And now it's disappearing, nobody has noticed its absence. It's London's own bespoke street light.
Today two motorways cross the Severn near Chepstow. But as recently as 1965, the only crossing was a ferry that carried six cars at a time, from Aust to Beachley.
