Block switch, for switching out block section on closure of signalbox. Block switch Signalling & Telecommunications
Signalling instrument, block switch, for severing block section on closure of signalbox, unmarked Signalling Block Switch Signalling & Telecommunications
London, Midland & Scottish Railway block switch for closing out signal box. Block switch, London Midland & Scottish Railway Signalling & Telecommunications
Signalling instrument, block switch, for severing block section on closure of signalbox, unmarked Signalling Block Switch Signalling & Telecommunications
