Hello Everyone. Borrowing this User ID to throw my twopennies worth into the ring. Being one of the foremost collectors of Dr Who props in the UK during the late 1980's and early 90's I feel I could be of some assistance in this thread.
First up in all the years of collecting I have uncovered ALOT of rare stuff, not all of which is public knowledge that it actually exists. Many of the Visual FX designers kept alot of stuff that was being thrown away, or just because they liked it as a personal keepsake. I have never heard of any sonic screwdrivers in existance. The last recorded one was of course made for "The Visitation", a Peter Davison story where it was destroyed. Although I have no concrete information the blown up one was probably made of plastic since it seems to warp when blown up, so the original Davison one would have been retained by VSFX or John Nathan Turner. Sadly when JNT, the producer died the Sonic Screwdriver was not one of the items that were sold by his estate which tells me someone else has it, since there is no way that an item of that importance would be lost. Peter Wragg, of thunderbirds and Red Dwarf VFX fame would probably be able to cast some light here since I belive Visitation was his story as VFX producer.
Now...about this "Thunderbirds" hand too that you guys have discovered. The connection here to Dr Who is something I thought widely known but I'll post it here in case u didn't know. Back in the late '60s/early 70's Century 21 went out of business and several BBC vfx personal including Matt Irvine found out. A truck was sent out and loaded to the gills with models, fake trees, computer banks and....wait for it....hand props. This discovery of the prop in Thunderbirds, and the awesome screen cap pretty much has sold me on the sonic screwdriver being one of these items, with the letra-tape added to break up the length and the satellite/bullet thingy on top. This is EXACTLY how the department worked because there was little or no money to make anything. So the question is, is this a found item. Well there letting would suggest that but I still feel that it was lathed, simply because the made so much stuff from scratch on Thunderbirds. Could it be some kind of shroud etc. put over the top. Who knows.
To find out the true history of the Sonic screwdriver is going to be very hard. Certainly I think there have been many variations. It's the kind of thing that would easily go missing, certainly be broken (Tom Baker and hand props....not a good mix) and most definately be stolen. As to its true origin simple....find the VFX designer on the story, write him a nice letter and I'm sure he will clue u in. They all seem like nice blokes and many in there 50's-60's now. Nothing better to do than play golf and remember the good old times at acton road.