Do we know these chairs ?  

I don't think we do:
http://bit.ly/1jH2X63 (link edited by DA)

Funny, I just came across that photo this past week when flipping through an Architectural Review. The chairs paused my flipping for a few moments.

A Scottish (?) architect unknown to many, including the DA database -- I wasn't allowed to indicate him on the initial new-post form . . .
http://www.historic-scotland.gov.uk/architectsvolume2.pdf

. . . and Leif's link gets me a red-lined response: Unrecognized thread. And yes, editing is not working.

Escuse me: "page not found." Was that your point, Leif ?
But the house is known online, anyway. Note the differences between the original facade (black-and-white photo, and revised (color):
http://www.themodernhouse.net/sales-list/farnley-hey-farnley-tyas/

I actually wasn't clowning around. The content management system failed to properly recognize the full link. It left "Østervig" off. (It isn't underlined).
So if you copy the link in it will go. Or if you google this, it will be the only search result:
site:designaddict.com farnley hey kurt østervig
And that is not to suggest it is a Kurt Østervig design. In the thread I mention that I think the chair looks like a Norwegian design, which would definitely suggest against a Danish designer. And I still think it looks Norwegian.
(edited by DA , the link didn't work because of the letter Ø , please use this link instead: http://bit.ly/1jH2X63 )

Hmm. Well, I really don't know my Scandinavian designers -- nor my obscure British architects. But I wouldn't expect a furniture designer to be linked to the architect of a house the furniture was photographed in -- would you ?
I like the cantilevered arm of the chair in the foreground. And check out the wood-clad metal columns outside the glass . . .

I am not sure what you mean about architects and furniture designers?
I remember this chair well because someone asked about it before in the context of a Farnley Hey House, and I rather fancy the chair myself--I tend to like Norwegian design--and so I put in a fair bit of time looking around for it. Unfortunately without any luck. Nor even the proof that is indeed Norwegian.

The chair in the background is a Rastad & Relling design (I.e. Norwegian) which proves nothing, but suggests something:

yep, the chair in the back looks a lot like a "Blinken" by Adolf Relling, 1956, Norway.

Looks like a Dux manta ray chair in the background as well.

Well know we know who made the chairs: Glostrup Møbelfabrik. I would not even venture to guess who the designer might be:
http://www.designaddict.com/forum/Identification/Glostrup-Mobelfabrik-Lo...