Apologies if this has all been discussed before. Recently I have rebuked a rather arrogant young Customer Services man in a station for repeatedly calling me "love" when I asked for information. I pointed out that he didn't know me and that I was a lot older than him. On another recent train trip there was a conductor who called the men "sir" and the women "dear". (In this case, he was a really helpful, cheerful man, and I wouldn't have dreamt of rebuking him, as I'm sure he meant no offence, unlike the young man in the station.) I don't see the need for any such form of address, but if one is needed, surely the equivalent of "sir" is "madam", is it not?