The button bolts are metric, and not many are carried here. He had something similar, once I showed him the picture. It is a bit longer, 10 mm, rather than 8mm. He said an extra washer should be the solution.

Perhaps, if the bolt being longer doesn’t mean the table can’t pivot properly. Everything is returnable here, he assured me. (update: items not needed at all. (ahem.) and were easily and quickly returned.

Perhaps tomorrow I will have another go at this puzzle.