Hi Robert,
For interest ...
The cane that has what looks like a possible butterfly centre is simply a distortion of a six-lobed "flower" pattern. I have the same cane within my own collection of Vasart / Strathearn weights, and it has slightly less distortion in one of the lobes.
I can confirm that the cane was in fact made at least as early as the Ysart Brothers (Vasart) period 1946-1955/6. Also I have a very close match to the canes in the inner row of the same doorknob. And the other two canes are also of a typical style of the Ysart Brothers period but I do not have an exact match for those.
Again, the the canes in the other doorknob follow the style from the Ysart Brothers period, but I do not have exact or close matches for those and they could just as easily have been made in the 1956 - 1964 Vasart Ltd period.
If you have, or can get, access to, a shortwave uv lamp it would be good to know how the clear glass fluoresces. If it is blue, then it is Vasart Ltd, 1956 onwards, or even Strathearn. If it is a shade of grey (definitely not blue) then it is Ysart Brothers period (or earlier) and would be, for me, the first confirmed case of a doorknob from those earlier years.