The "odd" one does seem likely to be a Vasart from the 1956 to 1964 period. I would not have been surprised to find this weight with either a "shaped" Vasart or Pirelli label on it.
But if the base had been rough-ground, then the same general weight could also have been from the earlier Vasart period 1946 - 1955.
However, to get a better idea about the period of weights like this one, it needs a UV check.
For more confusion, check my web articles (see my profile). For even more possibilities, with a better chance of getting closer to "Strathearn or Vasart", check Richard More's site.