Ashley Brown wrote to uk.transport.london on Thu, 10 Feb 2005:

It was a highly amusing journey, but had me thinking: what could cause
this sort of behaviour? How connected are the ATO and announcement
systems? Can the announcer get confused, but the train know where it
is? Could it have been the train operator initiating messages manually
and having a bad day/having a laugh?

I don't know about the Underground system, but I do know my mother
recently travelled via Southern from Clapham Junction to Arundel on a
train where the announcer went backwards..... There had been some
problems that day and a train had been cancelled, and the following
train was only 4 carriages instead of the expected 8, which may have
been why.
--
"Mrs Redboots"
http://www.amsmyth.demon.co.uk/
Website updated 23 January 2005 with new photos