Garry W

I've posted my old-favorite Lachenal concertina on eBay; it's at https://www.ebay.com/itm/203243728836 . I will also be posting my Jeffries soon. Question: people have told me that my Lachenal is indeed a Lachenal. But I can't find any actual maker's label or mark in or on the instrument. Is there a sure-fire way of knowing whether it is, indeed, a Lachenal? P.S. - If you're in the San Francisco area, you can come over and have a look!