Facts are sadly lacking in this area so this is pure conjecture. As Hobbs changed their body construction method from 4 bend to full 12 bend sometime into the early 20th Century it could be assumed that the Progress G became the Bankers and subsequently the SE1. This could have coincided with the general improvement to ABP Qualities by others around the period of WW1 as oxy-acetylene became more generally available with Ratner and Hobbs sandwiching ¼" copper within the door plates. Explosive resistance followed immediately after greatly improved by Ratner with their fully automatic Safety Bolt in 1918. The Tann device was initially a thermal device but served both purposes,
The term Bankers was used by most for their ABP grades and Branch Bank was the same quality but fully packaged with internal fittings such as teller’s cupboards and coffers.
Most of these improvements went for nought in the 60’s and 70’s as delamination side-stepped these measures.
The only illustration I have of the Hobbs SE1 is attached. The Branch Bank as I remember it was more or less identical. The door furniture was in Phosphor-Bronze.
Here are the specifications for the Progress Range circa 1910.
If all this doesn’t make sense blame the lovely person who took me out for yet another Birthday Lunch.
