Right Side Contacts Tension Adjustment Left Side
Cover Markings Base Contacts Tension Spring
Great Northern Telegraph Works - Cophagen

Model          G-N-T 6Ø5.58Ø5 Nic AWA
Base  material Wood
      size     4" X 8.25"
Aquired        March 2ØØ2
From           Thomas OZ2CPU
>I was surfing the web looking at GNT keys and
>noticed most do not have the wooden base.

This GNT model was made for the marine and was also used by the Danish rail road

In both cases they had the key directly mounted on the telegraph operator table, The key have no wooden base but a contact plate that is mounted in the table, it only takes a minute to unscrew the key and place a new one in the socket, there is no need to solder or unscrew wires.

If a GNT key (your model) have a wooden base, it has been handmade by a radio amateur or so on

Thomas - OZ2CPU

GTN Ad - 1964 ARRL Handbook