Oh Mr Hart, What a Mess!

That's an Aussie add reference BTW
Yes our code is a mess. It's interesting that both Alisdair and I have had similar problems with the iterators blocks, initialising things wrongly so we end up with accumulted stuff instead of a fresh copy each time.
And Alasdair found out that if you aren't careful about how and where you define your classes, WebBrick won't drop them... So you end up with really weird errors until you restart WeBrick