If we get to do the test at all, it'll probably be sometime next year. The dockyard closes to visitors this Sunday, and seeing as the tank we wish to borrow is in the smithery (essentially run by NMM/IWM) we'll have to wait until it reopens which will be sometime in the new year.
Neil, unfortunately if they did we'd probably already have it, but I'll ask nonetheless. I want one as well! We'll let you know if we do get the Shannon models whether it be just the one or possibly the whole set. From the photos I've seen of them I think they're about 8th scale like the Severns, they seem too big to be 12th.
If anyone wants to see the models we've got, on display and in storage, just come see us on a day we're there, and ask for me or Lance. Although I wouldn't recommend coming in the winter - it gets ruddy cold!