On the day prepay launched enough people with season tickets accrued
negative balances for the media to report it as a bug.

http://news.bbc.co.uk/1/hi/england/london/3422051.stm

There was of course no bug. All of those people did not have zone 1 on their
travelcards and for the first time the system was able to catch them out.

How interesting. I'd heard those reports and kind of dismissed them as
rubbish journalism stirred up by the Lib Dem candidate for Mayor, Simon
Hughes, who never missed a chance for a dig at the Mayor Ken and didn't
let such trivial things as facts get in the way!

That's fascinating to hear the real reason behind the 'Oyster bugs' was
the system working properly (and catching people out) rather than a
system problem. It's not called a smartcard for no reason at all! Is
your information from an authoritative source?

I think it was on the TfL/GLAwebsite but I can't be sure and can't find from
a quick Google. Prepay was launched Jan '04 so it was around that time.

It seems Simon Hughes can only get his name about by claiming that anything
he doesn't understand is "scandal".