Anomalously numbered roads in Great Britain

In the Great Britain road numbering scheme, the country is divided into numbered zones, the boundaries of which are usually defined by single-digit roads.

The following tables list all British roads which are anomalously numbered.

While the M25 may appear to contradict these rules as it runs through all the London-bound zones, it in fact does not: it does not quite form a complete circle.

The A282, which completes the circle mostly formed by the M25, is anomalously numbered; as it proceeds into the A-road 1-zone (and should therefore begin with a 1).

The M271 is numbered as a spur of the M27, as opposed to the traditional numbering rules; however the M3 to Southampton came after the M271 was built and is not the zone boundary, which appears to be a straight line from M3 J8 to Exeter in some documentation.