The 4 jaw chuck was an expensive option for the Adept, and it was only in later years, after the original chucks were no longer available, that people started fitting the chucks that were available, which were generally bigger than the standard. These larger chucks cause the issues described below, (from the lathes.co.uk site), courtesy of Mr Andrew Webster. I did try to contact him for permission to reproduce this extract here, but his email did not work. I hope this is OK in the spirit of the discussion. Apologies to all concerned if not.
Cast iron's most striking characteristic is its high resistance to sliding wear. Few lathes of the time featured pre-stressed ball or roller bearings. These were costly in the smaller sizes until the 1950s. The better large lathes therefore often had replaceable bushings of bronze or gunmetal, but many gave excellent service with a hardened and polished steel mandrel running in a lapped iron split-housing. Most, if not all, of the small model-maker's lathes had an unhardened mild steel spindle running direct in an iron housing. These were seldom polished or lapped, and the sometimes the housing was bored without reaming, like the Adept.
This being said, the longevity of this arrangement is remarkable if attention was paid to cleanliness and lubrication. It is nevertheless likely that an Adept or similar spindle will exhibit significant wear, especially at the tail housing where an excessively heavy chuck could cause headstock centre drop. Some owners fitted cycle oil cups which did much to keep things oiled. Some fitted fibre shims to stop oil running quickly out of the sawn housing. Others neglected the oiling, paid no attention to iron and corundum dust, and responded to heavy wear by screwing the housings together until they fractured. This is a common fault on small, old lathes.