I can categorically state that the Ditching Pre-Recorded Announcement cannot be triggered from the flight deck of a BA 747-400 and this was not triggered by a pilot as is being reported in the Sun and Mail. The PRA is a function that is controlled by the cabin crew along with all the other 'canned' announcements you hear on a BA jumbo. I very much doubt that this was a deliberate act, someone on the cabin crew of this service made an error, and is probably mortified by it.