How do you know it is 1909?
Is it a London Erard or Paris?
Can you tell us the complete exact wording that is on the front?
Are you sure the number you quote is the only number inside?
It certainly looks Edwardian, typical of the ones at
The photos you sent confirm what you already said, that is the likely serial number, and suggests 1909.
What sort of information are you hoping for?
The retailer is shown as W.F.Cole & Sons, Sheffield. They appear on our Sheffield lists from soon after 1899, so they probably were the original retailers. Near the bottom of my Archives page
there is some information about Erards, and a link to their online archives,
http://archivesmusee.citedelamusique.fr ... hives.html
and this page may help you...
https://archivesmusee.philharmoniedepar ... 5_81_P0001
There may be some listing of the original sale of this piano there, but I have found it quite difficult to work with. It seems to suggest the date as 1918.
After that, there is usually no way of doing active research on the life history of a piano.