Did the upholsterer remove the cambric under the seat and inspect the chair? If so, I’d believe what he advised.

how broken is the seat?

Do you know how many ties or springs are broken? If you remove the Cambric, is there jute strapping before you see the springs? If so you’d have to remove the strapping, and try to tie the springs where the cording is broken. Not impossible, but chances are it will never be as sturdy as it was before.

Is the seat the only part that is upholstered? If so, a new piece of leather for it might not be super expensive to replace...

It would be expensive because they’d have to replace the whole chair. Would be impossible to find a matching piece from 1940. Also would have to remove all the metal tacs and replace one at a time.

I'm not sure I understand the above comments - how can they 'replace the whole chair'?

And why would leather not be replaceable?

I meant the leather on the chair. The top and the arms are all covered with the leather, not just the seat.

If they just recovered the seat, the leather will be different from the top part and noticeable.

I have no experience with this, but I don’t see why it can’t be fixed. Sure, it might be tedious to very carefully remove the tacks so you don’t tear the leather and you might have to replace all the tacks if some break as you remove them. Maybe the upholsterer didn’t have the patience or couldn’t guarantee he could save the leather. My3dogs could advise you.

Maybe check with an antique restorer rather than an upholsterer?

An upholsterer I've used said that he could remove the springs and replace them with firm foam and webb the bottom closed. How long do you think such a fix would last? Here's a photo of the chair bottom.

“An upholsterer I've used said that he could remove the springs and replace them with firm foam and webb the bottom closed. How long do you think such a fix would last?”

That‘s how much new furniture is made. As long as the foam is firm, and webbing tight, it should last if it’s not abused.

That's why I asked if the seat is the only part covered in leather - the picture in the OP isn't very clear, and suero did not answer that question. The text notes 'exposed wood frame'.

Leather stretches and if this leather is 80 years old, I don't see removing & being able to put it back satisfactorily. But if it's just the seat, it could be recovered with new leather, I think.

P.S. I did a bit of searching and found this - is it the same? This looks like it was recovered with fabric, and the back is covered, but also looks padded.

If it's the same chair, judging by the asking price, it could be well worth repairing.

https://www.1stdibs.com/furniture/seating/armchairs/pair-of-early-1940s-edward-j-wormley-armchairs-dunbar/id-f_11940413/

Looks like the same chair to me. I like the fabric on it. Wow, what a price tag! Definitely worth reupholstering.

Here are the photos of the stool my relative repaired. Sorry no before pictures.

Yes, the chair is the Wormley chair. The back and seat are leather. The leather is in excellent condition. I did a little more investigation. Under the seat there is padding, covered by a heavy fabric. The 8 way hand tied springs come next, with the ties next to the fabric. There are tightly coiled springs that attach to the wooden sides, and two of those springs are missing. You can see the springs in the photo. Those springs are quite rusty, but the coils are not nearly as rusty. You can see a canvas fabric that partially covers the springs and is tied to some of the springs. Before I tore it off to see what was underneath, there was a very worn muslin covering the bottom.

I clicked on the 1stdibs link and now its ads are following me all over the internet.

ETA: Carolb, I don't mean this as a personal dig because you posted the link. I've done that myself numerous times. And I wasn't forced to click it! I'm just complaining about the nature of targeted online ads these days.