Tring Anglers http://tringanglers.org.uk/ are responsible for that section, you need a permit from them to fish so it is down to them to enforce no fishing areas or did you mean CRT warden?At local user group meetings they were always very helpful in resolving problems, but it works both ways.
The length from the bridge was certainly still no mooring 14 years ago, good luck with trying to find any documents the rule change if done whilst CC was waterway manager would be about 25 years ago, consultation you are avin a larf:)