I flew BA1, but it showed as BA0001 on the app and in manage my booking. It showed normally as BA1 on the website's "your upcoming flights", on the boarding pass (no wastage of ink) and on airport signage and everywhere else I can think about.

Is this due to BA IT gone amok (they haven't found out the code to drop all of those leading 0000s)? It kinds of clutter everything making it more difficult (BA0001 and BA0100 and BA0010 are visually much more similar than BA1, BA100 and BA10).