Sorry folks, but we need to be more specific when referring to "Vasart". It could mean Ysart Brothers (Vasart) [1946-1956] or Vasart Ltd. [1956 to 1964].
It's rather like the generic references to "Ysart" that can seen in books, eBay and elsewhere - which could actually mean any of: Paul Ysart [in four periods of pre-war, post-war-to1962, Caithness years, Harland period (three sub-periods)] or Salvador Ysart [pre-war, Ysart Brothers (Vasart)], or even Vasart Ltd [because Vincent Ysart was running the show until 1965].
Derek's dating shows that he is thinking of Vasart Ltd. However ...
... This weight shows features that could set it in either of the earlier or later "Vasart" periods. The only way I know to decide a date for a weight like this one is to view it under shortwave uv. Longwave uv (blacklight) will show it as a green colour for both periods and is therefore no help.
Because of the overall look and the base finishing, I doubt the weight is as late as the Strathearn years (1965 to 1980) but the continued use of Vasart (or "Ysart") canes in those years makes it difficult to be sure and this weight could conceivably be very early Strathearn!! And even shortwave uv cannot separate Vasart Ltd from Strathearn items.