Welcome to the forum - and sorry for your loss.
That looks like an Absolute Block instrument, used in a signalbox to indicate the 'state' of the lines controlled by the signalbox. In railway terms, the 'Down' line is generally away from London, and the 'Up' line is generally towards London. The arrows would be changed by a handle at the bottom of the instrument - it looks as though there might be two there, one for each line. You won't find this sort of setup in most signalboxes now, but there are some old 'boxes left, such as Moreton-in-Marsh on the Cotswold Line.
-Peter