According to brown Vol.I pg.85
John Rigby, grandson of John the founder, opened the first London premise in 1866 at 72 St. James street.
the Dublin premise trading as W&J Rigby at 24 Suffolk St. was sold in 1892 to Trulock and Harris. Most likely guns made in dublin would have been proofed in London, Brown states no way to differentiate gun being made in Dublin vs. london.
If you gun dates to after 1892 then it would have been made in London premise. This is a SWAG at best.
1865 - start at 12,418
1890 - start at 16,106
What is your serial number?
Hope this helps a little
H&H
