There are several distinct categories of signs which cause problems:
Prescribed: signs which comply with the regulations but which cause problems because they are misunderstood, hard to read, or often displayed at sizes which are too small
Non-prescribed: signs which local authorities have invented or placed contrary to the regulations (usually as a result of misunderstanding them) and for which they have not obtained special authorisation from DfT;
Specially-authorised: signs which DfT has authorised specially. These are usually by request from a local authority, but DfT has also issued special authorisations to all local authorities when it wanted to create a new sign without making a new Statutory Instrument.
Misused: signs which some local authorities use where they shouldn't. An example are Keep Left / Keep Right signs where the local authority wants to allow some vehicles (e.g. refuse lorries; utility vehicles) to pass the sign on the "wrong" side. The regulations for the signs themselves allow emergency services and some allied services to do this, but that's all.
[Diagram 618.3C for school streets]
[Flying motorcycle]
[Hammersmith & Fulham Blue "flying motorcycle"]
[450mm-diameter Width-restriction Signs]
[Minor Deviations: misplaced BUS GATE; new BUS ONLY road markings ]
[Merton School Zone signs]
[Yellow Plates for Motor Caravan Parking Restrictions]
[Keep Left / Keep Right]
Written 3rd November 2025; last updated 9th November 2025