I took a very similar photograph to this one back in 2013 during my last visit to Wigton, see....
https://www.ontheupfast.com/p/21936chg/30061915043/x12-wigton-signal-box-br-1957-up. However, I make no excuses for taking another as the number of mechanical boxes on the network has shrunk massively since then. The box is a standard British Railways (LMR) box constructed in 1957. I have no information as to what it replaced unless anybody can advise. It is now the fringe box from Carlisle. It does not look like the short siding to the loading bay behind me has seen anything on it for a long time! Re-visiting my web notes from 2013 reveals that I made a very similar comment then!