Whitewave that's a spot on description, My DM still has her "telephone voice" although we were my no means posh. When I moved to Middlesex & worked in Surrey (well spoken rather than posh accent) I did notice my accent changing but dealing with Accountants on the phone from all parts of the UK it helped to speak clearly, however I've never lost all trace of my Yorkshire accent, even here in Devon people often ask me what part of Yorkshire I come from 
People who come from money know how to treat "staff" in Bars, Restaurants, Shops, polite & appreciative of good service - new money is rude & overbearing, treat you as a personal slave
There's a saying up North "all fur coat & no knickers" for people who put on "airs & graces", usually when they're all top show, proper snobs of the Hyacinth Bucket variety 