Block instrument (lock and block)
Block instrument: Sykes' Lock and Block absolute 2-tablet/1-semaphore block-indicator with plunger-commutator, release key-hole, and switch-hook (all brass). The upper/lower tablet indications are "Locked/Free" and "Blank/Train On" respectively. The tablet cut-out face-plate sits within a brass-bezelled circular aperture and is inscribed "Local 12", "To Coborn Road", "From Devonshire Street". Above the tablet-aperture is a rectangular brass Sykes' maker's plate. This instrument was presented by 'W.R. Sykes Interlocking Signal Company Ltd' and has a Description Card.
This instrument was in service for many years on the former Great Eastern Railway line between London and Romford.