Saxby & Farmer signals have been in use since the 1860s in various forms, and often remained in original condition until the resignalling and line closures of the 1960s. They were particularly associated with the London, Brighton & South Coast, Great Eastern, Metropolitan, and Great Northern (Ireland) Railways. Some can still be seen on the Bluebell and other preserved railways.

The actual size of the fret is 96½ x 149mm; it is etched in 0.015" brass.

Identification & quantity of components on fret:
1. Early home arms (2)
2. Early distant arm (1)
3. Later stop arms (3)
4. Goods and calling on arms (2)
5. Spectacle plates (7)
6. Backlight blinders (7)
7. Goods ring (1)
8. Annett's distant signal reflector (2)
9. Balance levers (7)
10. Balance lever brackets (7)
11. Lamp bracket and bearing for arm 4 (1)
12. GER lampman's platform (1)
13. 4ft x 3ft brackets (2)
14. Bracket flanges (2)
"15". Later distant arm (1) - at top of fret