This comes from Garston somewhere - I have lived here all my life and don't know where it comes from or why - like you say - it has gone from 9.00 to 8.45 over the years. Someone must set it off because it is never right to the minute but always around then. I have asked before on another thread if anyone knew. I just know I used to run to school when I heard it - but now my kids know they have got another 15 mins!!