When the mechanical signalling on the ECML was replaced in the 1970s BR constructed a series of new gate boxes at strategic locations on the line to be able to provide emergency signalling in the case of failure of the standard systems. The rather utilitarian boxes were constructed to the same design and remain today ready to be put to use if needed. Built in 1975, the example here at Tallington is adjacent to the level crossing where the busy A1175 crosses the line where long tailbacks often build up. A similar example was photographed last year at Carlton, see....
https://www.ontheupfast.com/p/21936chg/26273761804/carlton-signal-box-br-1976