Earlier quoted context omitted.
> I do not know how bad it was, but it cannot be good the code was bad. I do know because I reviewed the code and its issue tracker extensively. I then wrote an article summarizing its problems that went viral and melted the server hosting it. The Imperial College code wasn't merely "bad". It was unusable. It produced what were effectively random numbers distributed in a way that looked right to the people who wrote…
Aside from the code quality, his models have never been close to accurate on anything.
Other models I checked didn't have the same software quality issues though. They tended to use R rather than C and be much simpler. None of them produced correct predictions either, and there were often serious issues of basic scientific validity too, but at least the code didn't contain any obvious bugs.