Dating Jeffries by their ends?

[Ptarmigan]

Stephen Chambers just posted an interesting observation on a nearby thread today, when talking about this Concertina on eBay:

 

Also, original metal buttons of this vintage are of a very small diameter, almost like knitting needles.

 

Nice Jeffries on eBay

 

Which reminded me that anyone who has played my 45k Jeffries, including the likes of Dave Prebble, usually remarks quite quickly on how small & narrow the buttons are & the fact that they're not very well worn either.

 

 

So when did Jeffries start using Metal Buttons & were the early ones really that much narrower than the ones they used later?

 

Or are there numerous variations on this aspect too, just to confuse us all, even more?

 

Cheers

Dick