These are all based on BS1363, however all have at least one incompatible change, so that they can only be used with the matching non-standard socket.
Such things are typically used for sockets in public places or other areas where sockets are only for use by certain persons or for specific types of equipment.
Standard BS1363 plugs will not fit into these sockets, and the non standard plugs cannot be used in standard BS1363 sockets either.
Some of these devices are still available, the MK type with the T earth pin is probably the most common, and the round earth pin variety can still be purchased new.
The others such as the Walsall Gauge have not been manufactured for many years, although examples still exist in older buildings.
The electrical museum has an entire section on these non-standard 13A plugs.