Originally Posted by
Johno59
Nearly every British bike I have has this arrangement. Sunbeam, Rudge, Triumph, Hercules, Humber, Holdsworth, Claud Butler, Bates, Raleigh, Robin Hood and some.. That goes from 1903 to the 1980s when it all went pear-shaped. For what it's worth it was a terrible PITA if you were a mechanic. I'm assuming the idea was to keep the BB as narrow a possible - if I'm being kind.
...I always assumed it had something to do with giving maximal access to the cotters, for removal and reinstallation. It's my own assumption, and might be wrong. Might have just been ease of manufacturing, given the machinery available, and the limitations of it.