Telegraph block intstrument (permissive)
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Telegraph block instrument; BR (LNWR-Fletcher's Style). Combined single-needle permissive pegging 3-position/3-indication. Traffolyte-plated "Down Main" and "Chester No 3". Circular bakelite-commutator/permissive tell-tale window is set in a large brass disc. At RHS is 'permissive' plunger and blockbell-tapper is at bottom RHS (door) with underslung bell-dome. Ex. 'Chester No 4' signal box.
