Although upper quadrant arms had been in use since shortly after the Grouping, the tubular post signal dates from the mid-1930s. It was used for new installations and renewals until the end of the Big Four period, and by the London Midland, Eastern and North Eastern Regions of British Rail(ways). The design does not appear to have been common in Scotland, probably because most pre-grouping signals had lattice posts, which would have remained in better condition than the timber posts used south of the border. Many examples are still in use today, and new ones are still being installed where replacement by colour lights is inappropriate.
If you wish to model a taller signal, add a G1/09 ladder to your order.