Good luck to all of you about to take various parts of the test.
Actually, it's not just the change in speed limit signs I have a problem with...they're usually straight forward. It's other signs that are not always familiar. I was able to identify them on the theory test but don't always notice or register their meaning in my consciousness whilst driving.
Quite a few of the modern British signs are pretty illogical and inconsistent. For example, the no left/right turn signs are clear enough, depicting the appropriate turn arrow crossed through (basically the same as the equivalent newer American signs). But why do other prohibition signs for no bicycles, no motor vehicles, etc. show the symbols
without a bar crossed through them? It makes no sense. When you get to things like the no parking and no stopping signs, you just have to know them. There is no way you could even start to guess at what they mean without having some clue to begin with.
Modern British signage (both regulatory and directional) stems from the changes recommended by the Warboys report in the 1960s, which introduced a lot of graphical signs adapted from Continental Europe to replace our older signage, a far greater proportion of which spelled things out in plain English wording. It's interesting to note that at one point they were considering adopting some American-style signs, so had the committee decisions gone a different route, we too could have ended up with some U.S.-influenced signs (if you've ever visited the Irish Republic, you'll know that they use yellow diamond warning signs instead of red-bordered triangles).