This is around 1890 to 1930 concertina .From the fretwork, the hexagonal wooden ends, the hand strap, and the lettered buttons, this appears to be an English concertina rather than an Anglo or Duet. The English layout often has letters stamped on the buttons such as this - and the velvet inside the box is typical of era . The bellows have patterned papers and green leather corners — a style strongly associated with Lachenal & Co., one of the biggest makers of the era.
The bellows wear is typical for a 100‑year‑old instrument and doesn’t look catastrophic.