This is another variation of the Benson type scope, although instead of a clamshell hinge the two lenses rotate through the same axis about a central hinge.
One side of the ophthalmoscope is marked Plane. Rec No 350 669, 350 671. The mirror on this side shows signs of ageing. The other side is marked concave, Curry and Paxton’s. London. Bickerton’s dual retinoscope.