That box is gorgeous! I have a very similar one dating from 1932, and I guess yours is probably a little later, seeing as the decoration is more like the pokerwork melodeons, which have been in their current form since the 1950s. All in all, the pokerwork pattern, wooden grille and casein buttons point to it being mid-late 1930s.
This one below is mine - you can see the overall shape is very similar to yours, but the keyboard ends are a little more exaggerated and the pattern, while still pokerwork-esque, is very different. You can't see the grille, but it's essentially identical to yours.
This one in the eBay listing is similar to yours - the pattern is identical, but it has keyboard ends like mine, and mushroom buttons like a pokerwork melodeon. There are obviously a few designs of pokerwork piano accordion, but I've never seen a 24 bass like yours before!
<p dir="ltr" style="margin-top:0; margin-bottom:0;">Vintage Honner Keyboard Accordion - Black & Gold - In Original Box.</p> <br> <p dir="ltr" style="margin-top:0; margin-bottom:0;">Used item</p> <p dir="ltr" style="margin-top:0; margin-bottom:0;">Good condition</p> <p dir="ltr"...
www.ebay.co.uk