The M45 is a spur from the M1 in Northamptonshire, westward towards Coventry. Today it just provides access to part of Coventry from one direction on the M1, but its historical significance is much greater.
The wait is over! The full map of the Ringways, London’s unbuilt urban motorway network, is now online. Not even the system's planners had anything like this.
The most Frequently Asked Questions where British Roads are concerned, and the answers. A good place to start if you're new to the subject or you're looking for quick facts.