One of the most disturbing aspects of the story about tube announcer Emma Clarke (who's been sacked for recording spoof messages on her website) is the fact that she's not at all posh in real life. I saw her on the news and she comes from up north somewhere. Her cut-glass accent on the underground - "in Hertford, Hereford and Hampshire, signal failures hardly ever happen" - is all put on. It's a case of My Fare Lady.
They've recently introduced posh announcements on the 281 bus route between Tolworth and Hampton in south-west London, but I think the messages are lost on the people who are travelling. In reality, they need to record stuff like: "Get off da bus now innit cos da feds is checkin ur passes at kingston."