Concertina valuation

[Proust22]

Hi I'm in the UK & I've inherited a couple of old concertinas, both in what appear to be original boxes. One has the Lachenal paper ID & number 39260, has five bellows which look original with some age damage, 48 buttons. The other one looks exactly the same (ish) but has no paper ID, but has the number 142298 inside it over a stamped 'R'. 

How would I find out whether these are worth a lot, or not? Thanks for any advice/guidance. P

[Bill Crossland]

Pictures would be useful.....