It's never simple! I'll look for a part number under the paint and take it from there. I wonder if a post-war sleeve will fit...?
It can be easy. John has a correct early top yoke for sale for a M20 (see wanted/for sale section). Just buy that 1 and sell the one you have now. It can be difficult to make the correct sleeve and fit it properly, someone in the Netherlands told me as he did this.
