MANUFACTURED in 1961, Serial No. 29331.
The C4 had four magazines allowing type up to 18 point, and used sliding carriages to help ease the changing of magazines.
A High-Speed version was introduced in 1954 that used Teletypesetting (TTS). TTS is a means of automatically selecting matrices using perforated tape running through a special attachment on the machine.
The Whittaker machine does not have a TTS attachment, and appears to be the standard version of the C4.