I'm fairly sure this factory pattern relates to Registration 328744 dated 4th November 1878 - there were in fact twelve Registrations on that date.
Have a look at the attached and tell me if you disagree.............. starting at the top and working clockwise, Keith, the details on the diamond should read.... 4 - D - 11 10, and of course it will be from the second period lozenges. I'm assuming that the '1/2' size is just a smaller example. It's apparently described as a vase, but looks to me more like a bowl.
The original factory drawing appears to show three legs only, but am sure that's just the artists way of showing the legs on the drawing, since yours does have four, and as is mostly the case this Registration is protecting the shape rather than any decoration.
Very nice by the way. Personally I found the '20th Century Glass' description confusing........ If I didn't know better, I'd be unsure as to what to call this..... milk glass or Vitro-Porcelain or Queen's Ivory .............. I'm probably being thick, but from the wording it appears that these terms are equal and interchangeable, which of course they're not.
Anyway, let me know if you agree that pattern 1350 equates to Rd. 328744.