Joe / Tom,
This early M-H 12-20 was restored in the North West of the UK during the 1980's, it was then sold to it's present owners a few years ago through the Cheffin's vintage auctions near Cambridge, since then it has had a new Rosewood manifold fitted, together with a new serial number plate from Chris Astell at Vintage Brass Plates here in UK, I am surpised they went with the Wallis 12-20 plate too.
The tractor was subject to a very intensive restoration which was done very well in the 80's, it had been seubject to our bad weather for many years as you noticed Tom.
I am surprised with the early serial number that this tractor does not have the round tubular steeriing shaft post bolted to the footplate, has it been converted to the angle iron one bolted to the fender? I know of one or two other early examples with this feature.
My Wallis 12-20 has the three holes in the footplate for the round tubular base plate, but again it has the angle iron support..