This was - perhaps - the hardest (upholstery) job I've ever had.
I can't find any information on this most unusual style of chair (let me know if YOU know!)…
it's basically a mattress-type of sprung system, held together with steel straps, which hook onto the frame in only 2 places - the outside back top (shown) and the front seat rail.
It was necessary to remove the 'mattress' and upholster that, then hook it back onto the frame, then hand-sew the fabric closed.
MUCH harder than it sounds.
End result looked OK - but more importantly (and surpising to the clients, whose family this has been in since at least the 1930s) it's now supremely comfortable.
I replaced the mass of flock stuffings with high density foam (dacron covered) - and sitting in it now is a bit like sitting upright in a very supportive hammock.
Result: clients delighted.
Phew! (I'll be quoting much more for the next one - if ever!)