They’re most likely table numbering or possibly Cabin numbers.

There were quite a few ships in the Houlder Fleet and they were probably made circa 1920 - 1930’s. 

Houlder Bro’s had a fleet of Steamships operating from as far back as the mid-1800’s

Houlder Bro’s & Co commissioned the merchant ship “Hardwicke Grange” out of Glasgow in 1921 and it was sunk by a German U boat (U129) in 1942 in the North Atlantic. These napkin rings may well have come from the Hardwicke Grange or a sister ship. Several of their fleet were sunk during the 2nd World War.

They are all in good condition - with minor blemishes as you’d expect with their probable age. 

They measure 4.5cm in diameter.

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