Frog I heard 'the rule of thumb' thing on Radio 4 - so of course it is right! LOL
language is not stagnant it is constantly evolving and takes on new meanings all the time. So I think it is fine to say rule of thumb to mean a standard... I just find the origins of some expressions (such as nitty gritty) really interesting. Anyone know a website with these things?

Salax one of your first posts here was to try and get a girlfriend and make a dating section to QL. Now you say it is ok to hit a woman. I hope you enjoy being single because no woman wants to go out with a man who justifies violence in anyway.