As I said, maybe I need to write this bigger.
THE RECORDS DO NOT EXIST FOR THAT PERIOD
the last entry in ledger 4, in 1847 is s/n 222510
the next entry in ledger 5, is 1854 is s/n 260376
with the missing records being destroyed in the Blitz along with Chubbs London offices.
Having looked again at your posts and pictures I (with my mere 30+ years of collecting and knowledge of Chubb) am quite confident that your lock is an entirely ordinary lock of it’s type. Which has almost certainly been taken apart.
There is a slim (very slim) chance it does have one slight (but by no means unique) technical difference but I’m not doing to bother to try and explain it.