Catalogued items always have a registered number which starts with two initials, referring to the designer.
A lot of the 'Tordus' séries is done by Rene Delvenne, but I came across several similar bowls in the 1962 catalogue, done by Pierre Dias, so I would opt for him rather then Delvenne.
I always have mixed emotions when I see these free form pieces, because of what and the period they represent. This type of glass was extremely popular at the time and the company directors took a big risk by trying to milk it out, the production that is, as much as possible. For the professional glassblowers, it didn't leave much of a challenge making these pieces anymore and a lot of these pieces ended up being made by apprentices. Because the direction insisted of focusing solely on this glass, due to it's popularity, no new exciting designs were made, glass cutters had less work and new designers were not taken on, very much to the glass blowers worry and annoyance ... to make a long story short, this type of glass got overproduced and the market collapsed. Unfortunately VSL never recovered from this, and I guess we all know where it lead to.