Telegraph block instrument
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Telegraph block instrument; Midland Railway Langdon 3 position sending type. GER pegging/non-pegging 2-needle 2-position/2-indication absolute with a vertically-mounted large brass flap (painted black on one side and green on the other). A small brass red "Train on Line" reminder-flap is also attached covering either one red brass plunger (LHS) or one brass white plunger (RHS). Case stamped "MR Co".
