I know on the occasions I've spoken to you on the phone, Bob, I'd never have guessed that you were originally from the West Midlands, the accent from which is highly distinctive as we know. You sound like a guy from the South. It's funny, some people never lose their original accent, whereas others, probably the majority, do. I've lived in Warwickshire since 2001, and didn't think I'd lost my Essex accent - but when I return home, they say my accent has changed, and I pronounce some words differently.
As for the 11mph limit, no idea. There may be a perfectly logical reason for it, although this is the 21st century, so logic probably doesn't enter the equation. I'd suggest to @blakeyboy that he contact the relevant council, but I'm not sure there's any point.