I've been away for most of June and July, and looking at my usage meter, I can see that my bit torrent client (Vuze) was happily uploading until 10am on 1st July 2012. Now I am home, I have successfully downloaded more (from thebox) but still no uploading activity. It could be due to a windows update, but I thought it could be due to some change that TC have made, and if that's the case, other people might have experienced the same thing.
Very strange. The port mappings were set to the wrong local network address, corrected them and it seems to have cured the problem. Thank you. What I don't understand is how it worked before, when it certainly wasn't manually changed at the time the problem appeared.