Telegraph block instrument; Metropolitan & GCR. Spagnoletti sending type; single-vane pegging 3-position/2-indication (Down Line). Above this is an engraved-traffolyte plate inscribed "Northbound", and below is the commentator-assembly comprising 2 keys (red/white), a sprung metal-rod slide (to hold down either key, when in depressed position) and a rectangular equally-divided brass-bezelled case inscribed (LHS) "Train On Line" and RHS "Line Clear", complete with a back-cabinet.