I'd take a guess that the recent problems with the TSB migration are down to something like this. (Google it if you haven't heard). They tried to replace lots o

I'd take a guess that the recent problems with the TSB migration are down to something like this. (Google it if you haven't heard). They tried to replace lots of ancient systems with a big new one and ... it didn't work. Root cause on something like this is problematic: management instituted a hard deadline despite signs of serious problems early on, and there seems to have been some monkey patching being applied to live systems as they try to get it working. But a big factor has got to be the huge problem of figuring out what all those old legacy systems actually do.