C100

OpenStreetmap shows a tertiary road labelled C100, runnning from junction 4 on the M40 (Handy Cross / High Wycombe) to Marlow.

The first time I saw this, I thought it was a mistake. The road exists, but the number C100 doesn't seem to appear anywhere else, and while we all know A- and B-roads, I've never seen a C-road before.

But then, by Googling the Interweb, I discover that there are references to this road as C100 in several places: here, on the Highways Agency Site; here, on the Buckinghamshire county council site.

What's more, there are loads of roads with C-numbers, used by local authorities to keep track. Some authorities also have D-roads, and others have U-roads. There is more detail about them here. As a general rule, C-numbers are not released to the great British public, but it seems that some escape.

Someone obviously knew what they were doing when they described this thing as the "Information Superhighway" (remember those days?).