Jim,
That is indeed a 48-key English concertina, and a desirable instrument of good quality at that. However, I think you must have mistyped the serial number as 24805 would have been made around 1909, whereas yours is a "dead ringer" for the ledger description of 28405, which was made around the date you quote.
Sorry my mistake, the serial number is 28405!
I gather it is a model 22 which I was not aware of.
Thanks for the reply.
Kind regards; Jim