My early 3 piece oyster cas has no reference number??

[Natless@live.ca]

This one has me baffled. This early oyster case has no reference numbers. I saw a similar case on Ebay with a Tudor movement that also has no reference number. Any feedback on this? It's real and fresh from a watchmakers estate. Thank you for your feedback!
Cant seem to upload pics. It is the same but a touch smaller than reference 2081. The inside cashback is marked oyster watch co with all the trademark dates. The serial number is 44 xxx. There is not a reference number between the logs. I checked at 10x magnify. It has a lockdown crown