"J" mark before the O on the Hallmark

by David
(Warrington, UK)

We are trying to date the ring as attached! Using the British Hallmarking Council book we have worked out the assay office mark is London, and has the Crown & 22 next to that!

with regards to the date mark it looks like the mark "O" from 1909 but it seems to have a J in front of that what does that mean? It looks like the ring has been altered at some time would that be the reason? Regards, David....