> http://webexhibits.org/daylightsaving/b.html
> > 
> > All the references I've found on the web (including the BBC) 
> > say that it (BST) begins and ends at 0100 hours. In the U.S. 
> > the time is 0200 so the issue of "Is it today or yesterday?" 
> > doesn't come up.
> > 
> > > When the clock is turned back at the end of Summer Time, does 
> > > the time then become 00:00:01 of the same day or is it set 
> > > back to midnight of the previous day?
> > 

The reference above says that BST ends at 01:00 GMT, i.e. at 02:00 BST.

Michael Kay
http://www.saxonica.com/