Post Office GPO Square Seal (Round Version!)

Post Office GPO Square Seal (Round Version!), Image & Found by Redgy Dewulf.
Found on the Continent, ?mm.

...ORD / corrugated markings / S.S 3 // ? / corrugated markings / illegible inscription

The markings show it to be a Post Office letter bag seal but this type has only been found in square form before, see BSG.BS.01461.