Here are a few Perfins, starting with some from Bristol. The first is from John Lysaght Ltd, an iron and steel company in 1920. [A perfin is a postage stamp perforated with the initials or insignia of an organization to prevent misuse.]
Great Western Railway (GWR) were prolific users of Perfins, this one is from 1927.
Colthurst & Harding Ltd was a paint manufacturing company. The windowed commercial envelope below was posted in 1935.
Bristol Corporation (BC) was probably the largest user of perfins in Bristol, the pieces below were receipts bearing a perfinned stamp in 1952.
Moving into Somerset, the commercial postcard below from Langport in 1903 has a "K&S / L" perfin from Kelway & Son Ltd.
The commercial envelope below is from 1899 with an "ABB" perfin from the Anglo-Bavarian Brewery. The firm suffered a decline during WWI because of their apparent German name.
Small & Sons in Taunton sent out this bill in 1946.