I think you are wrong.. I have always been told MI over ride everything else and this is what we trained out at BG[/QUO
have a read at your IUP, i have listed the info as it is listed there, and remember the building regs will reference the MI but one that springs to mind is flues next to a boundary of a semi detached borderline, if you quote MI the flue needs to be 300mm from an opening, so you fit the flue on your side of the fence (obviously) and measure and confirm it is 400mm from next doors openable window so you have complied with the MI next door complain to you about the "white smoke" entering their prop, you tell them its nothing to worry about as anything over 300mm is safe, they say "aye right i'm away to the cooncil" who do you think the building control will agree with? (i know they will agree with the neighbour and can issue a non-conformity order making you move the flue, so who's the daddy? the MI or the local building regs?