This is a common enough type of MH plough spanner. It is simple - just flat steel. There are however several variants of it about with different lengths and some with none or only one of the small holes. They are only marked MH with no numbers.
Salvation is at hand however for sorting them out. I saw "Alan the Spanner" this weekend and he is making good progress on getting up his listing of MH spanners made around the world. But he still needs a lot of help particularly from Australia, France and South Africa. Please - if you can help him do so - it is a very worthwhile cause to get all the MH spanners around the world listed. We need more people like Alan to pull together the various aspects of MH history. Such efforst make for a good winter pass time.
John