Hi willgoy,
All these knives would be classed nowadays as "bench-made", made in batches of varying size.
The five blade Needham has chased backsprings, that work would have been done using small fine punches and chisels, perhaps a specialist little mester doing that kind of work and nothing else. The filework on the other knives would have been done using files or wheels.
While we are on a senator theme, I would like to show these few examples all marked
W MILLS & SON, SHEFFIELD, ENGLAND, these penknives were made later than those shown above, perhaps from the 1930s onward.
All these knives were made by father and son Willis and Ernest Mills, who both worked at Thos Turner & Co before starting out on their own C1922, Willis, once a top man at Brookes & Crookes and Thos Turners retired in 1947, Ernest in 1985 at the age of 85. The two man firm made finer types of pen and pocket knives for companies such as Wostenholms and Rodgers, plus high end retailers Harrods, Clements, Landells, Dunhill etc.
Top, 1. ivory n/s tipped 3 5/8" 4bl, 2. t/shell 3 1/2" 4bl. 3&4 pearl 3 1/2" 4 bl. 5&6 stag n/s bolters 4bl, all knives have brass liners, stainlass blades.
Thanks for looking..Mick