Ron
Thanks for the reply. On these occasions someone running an old British bike can always organise something. I noticed some knurling on both the nut & I'm fairly sure on the driven end plate,these on the end plate would presumably engage the head of the long through bolt?

There should be a cup shaped star washer under the nuts to fit the shape of the hole. I find that using a flat one is OK as it will change shape and grip once the through bolts are tightened.

ian
Thanks for this. The word "knurling" I used in the previous post was the best I could come up with, but it really looks more like the indentations you might expect these star washers to make.