The standard tubular steel signal post used by the LMS and LNER and their successors since the mid-1930s. The post is also suitable for the GWR/BR(WR), if you don’t mind the butt being 4mm too short.
Cast in brass, lamp brackets and arm bearings for home and distant arms (6′ spacing) are included, as is a peg for “planting” into the layout. Viewed from the front, the arm bearing is always on the left, with the lamp being to the right for the GWR/BR(WR) and to the left elsewhere. The cast-in lamp bracket is to the rear so the lamp can be placed either side. You will need to cut off the existing post cap and fabricate a new finial for the GWR/BR(WR). The post may be cut for use as a bracket signal doll.
Many are still in use today on Network Rail, and some are still being installed where colour light signals are inappropriate.
(There is only one post per pack; the photo has two to show both the side and rear aspects.)