Bought this one on eBay (Gwulo insiders will guess why). It's a pretty small photo (7,5cm x 5,5cm), but it shows the clearest view of Barker Road Houses I've seen so far for early photos. My estimate is 1920s or 1930s, any better judge is welcome.
I think the photo was taken from Plantation Road, some 10-20m above the junction with Barker Road. The roof in the foreground right therefore should be "The Cottage". The next houses along Barker Road are not visible, the next is "455 The Peak, R.B.L. 150".
Not sure with the house on the ridge, possibly Hazely? Downhill is "RBL 155". Further counterclockwise is "Cragside" (only the roof is visible), then "Altadena". Most prominent is "Richmond House" with the curved access road. Right hand side behind this house is a smaller one, probably servants quarters. Below Barker Road is "Martinhoe".