These components represent the type of signal used by the Midland Railway from the 1900s onwards, through the LMS period and into BR days. Lower quadrant arms were still much in evidence in the late 1950s and it was only in 1960s that the majority of Midland posts received upper quadrant arms (SN12/2), while still retaining most of their earlier fittings. At least one lower quadrant arm can still be found on Network Rail today, along with several on the various preserved lines.
The actual size of the fret is 44½ x 28mm; it is etched in 0.008″ brass. For clarity, the photo shows the equivalent 4mm scale fret.