Old mate John Beeston was upgrading the radio gear on his yacht and kindly passed the old manual antenna tuner to me. It's a Wagner AX-200 Manual Antenna Tuning Unit clearly designed for matching to the back stay short vertical wire.
This is a fantastic tuner for long (or not so long) wires. I threw up about 5m of random wire and laid down a short counterpoise and this gadget matches it on 40m perfectly and it's easy to tune by ear and then peak using the meter or the rig's SWR meter.
So far I haven't been able to find any reference to it on the internet and would welcome any specifications you might have.
There's a bit about Wagner on the net from Malcolm Haskard.
I can see that physically it looks very similar to the ATU1A. Here's a picture from an eBay auction:
If you stumble across one, I'd recommend it although it's not small enough for use as a travel tuner.