Robin,
I see that we shall not agree on this matter. Apart from the terminology 'cam' and 'peg' being used by Bishop Cam themselves it was also the terminology used by A.C. Cars Ltd. However one should always go back to the most original source possible: In this instance it seems to be the patent application of Reginald Bishop dated 1923. This extract is lifted from a Morgan Owners Club article:
"GB 223963 “Improvements in or relating to gearing for steering mechanically-propelled vehicles and
for other purposes”
This, a patent for a steering box, was applied for on July 25 1923 and has a publication date of 27 October
1924. The patent holder was Reginald Bishop, a Middlesex engineer, for a device operationally consisting of a
cam of helical form and constant diameter (at the lower end of the inner steering column) imparting motion via a
roller or peg attached to a lever projecting from the steering rocker shaft."
The salient feature of the system is a cam. It is not a worm. The patent exactly explains this in the phrase 'of helical form' in other words were you to unroll the helical member in to a flat form you would see a rectangular plate with a single wide slot running diagonally across it. Anything engaging in that inclined or cammed slot (you might use a peg) can only move horizontally if it also moves vertically. In our steering box the 'horizonta'l movement is provided by the driver turning the steering wheel and the 'vertical' output is applied to the rocker arm and shaft via a peg.
However I fear the topic is rather obscure and one should desist from boring the readers. It does raise something more interesting though in terms of nomenclature and I will start a thread in the more appropriate General Forum.