The chair in the photograph is described in print as "a 'Clissett Highback chair', an elm ladderback armchair with rush seat made in the Cotswold workshop of Ernest Gimson and Edward Gardiner and named after the Hereford chair bodger Philip Clissett who taught Gimson the craft".
Close examination of this photographs indicates (to me) that this chair was actually made by Philip Clissett himself - based on the shaping of the slats and finial. In addition, the photograph is data c1904 which essentially counts Gardiner out as maker. There's plenty more wrong with the above description of the chair.
The chair would, of course, have been made from ash rather than elm. Clissett wasn't from Hereford, but from Bosbury in Herefordshire, close to the border with his home county of Worcestershire. Clissett wasn't a bodger (a Chilterns maker of turned parts) but a chairmaker - he made complete chairs. It can probably be argued that he didn't teach Gimson the craft as Gimson only spent a short time at Clissett's workshop, doesn't appear to have learnt how to make rush seats, and wasn't very good at making chair frames, according to Edward Gardiner.
Details of Barn Close, Scott-Nicholson and his Clissett chair came from:
Whittaker E. (2018). On the Border: Barn Close and the evolution of the Arts and Crafts interior, 1902–1931. The Journal of the Decorative Arts Society 1850 - the Present. No. 42 (2018), pp. 90-109