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jimps :)
little screwdriver or brass brush cleans them fine.

Well ours are a bit different and I use home made ones anyway.
(Aluminium or Cerium oxide and Shaving cream)
Maas or Flitz might do.

Its bone, isn't it?
The mildly abrasive sink / steel cleaner works well there.

This is one beautiful and in this condition quite rare old sheffield.
Of course its possible to remove the little rust. I would not sand and polish it entirely though.
They never had a hi gloss...