Black enameled metal frame lounge chair?  

Hello Folks - I have a pair of chairs which have me stumped for ideas. These have a black ensmeled metal frame but are quite light. The design snd quality of the seat base spring seems quite good. The seat back cushion secure to the chair with press studs into the material covering the seat back. The black wooden legs have self levelling glides. They came to us with some other seats which are 1960s or early 70s, but I can find no markings on these ones and have not been able to make any identification. Any help identifying these would br great - thanks.
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