I got this Protector lock from ebay:

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The screws are nicely numbered by dots from no dot to three dots. The imprint is very weak, but I believe it is the same as on the lock above, i.e. HOBBS&Co PATENT PROTECTOR, CHEAPSIDE LONDON.

Any idea on dating that one? The serial number is probably 04800, so it is perhaps an early example of this 8-lever powder-proof lock? If so my guess would be around 1880-1900.

Thanks for your opinions