A (new) collection of (rather old) letterheads is currently in the process of being digitised and presented online!
From the Bill Lind Collection, the images aim to capture the graphic design of an era. Many of these companies, often industrial manufacturers, are no longer in business, so this collection, whilst primarily illustrates the visual impact of letterheads, it also lists forgotten names in Britain's long industrial heritage.
This is an on-going project, that will be added to over the coming weeks and months...the first batch is a look at letterheads dating from the 1920s through to the 1960s.
Just a couple of examples - check out the every growing collection, where you can view the full letters at The Ballast Trust on Flickr - Letterheads.