Old lock recovered from dredge material need help to ID/date

[OldGold74]

Hope some one can date this its important, it had GR and a crown with the word patent alongside it on the key cover, the lock is iron the face is brass any help appreciated, Chris

 

[chipveres]

Please see if you can read and Google the markings on the keyhole cover. These may be your best clue.

Chip V.

 

[allen_idaho]

The Crowned "GR" is not the manufacturer. It is the royal cypher for King George. The "GR" stands for "Georgius Rex".

This places your lock as being British in origin and from roughly anywhere from the 1714 when King George I took reign to the 1930's when King George V had died.

However, cyphers are entirely dependent on the ruling monarch's name and title. The crown usually denotes "king" and the initials denote the ruler's name. For example, GR was King George line (1-5), Edward the 7th is EVIIR, Queen Elizabeth II is EIIR.