Jigjag, thanks for your two posts - I missed the earlier one with the Sir/Miss/madam stuff. I think the 'sir' and 'miss' in schools is a very old way of doing things, but it's still incredibly useful and I can't think of anything that could replace it.
I'm a parent and if anyone in a school setting had ever called me 'Madam', I'd have felt obliged to put them straight! Unlike your Head, I'd never feel comfortable being addressed as 'Ma'am' - I think I'd have to say, 'please call me Ms (or at a pinch, Mrs) Malone.'
PS And I always prefer 'women' to 'ladies' !
NORAH is quite an unobtrusive but efficient organisation, usually working away quietly in the background.