Woodstock Indistrial Supplies (01202 474222 – http://www.nutsaboutbolts.org/doublecoil) have a range of metric double coil (Thackeray) washers. It looks like the M20 washer, that’s 20.2mm id x 32.2mm od x 14mm high, is the nearest (although the od might be a bit big). I will try them and report back.
If anyone knows of something better (or has a pair of originals to sell) please let me know.
Chris.
