I'd say that definitely makes most of them illegal then !!

One change was an industrial estate that's been 40 for decades....suddenly 2 small signs appear on lampposts at the 2 x entrances to the large estate ( and speed camera vans within of course )...friend gets nabbed for doing 38...in a 40, which is apparently now a 30.

The entrance he used had a sign about 5m in, on a lamp post on the left side as you drive in mounted about 5m height. In a car/small van the sign was actually barely visible when driving in.

So I queried via FOI about the change and legality. They said the area was always a 30, they just never signed it LOL. They also said they did not need to advertise any changes etc.

About a year later the sign was moved further in onto the next lamppost and lower down. But still only one sign.

The other entrance has 2 signs on new poles at a sensible height.