Tyers numbers 3 and 6 tablets were identical but only No 6 instruments were "returnable", that is its tablets did not have to pass through the section. The purpose of this was to allow passage of the tablet to an intermediate siding for shunting to take place before being replaced in the originating instrument.
No 3 instruments were "non-returnable", a tablet had to pass through a section and into the next instrument before another train could be signalled through.
4 7/16 inches (112 mm) diameter.
Boscarne Junction to Wadebridge East was the penultimate section of the L&SWR's Waterloo (London) to Padstow (Cornwall) line.