Thank you for looking, Paul.
Chris and I are both aware of the triple vase from Sowerby RD 324322 of 29 July 1878 (Sowerby pattern no. 1326, shown on page 6 of pattern book IX, 1882) – I believe Chris recently had one in clear flint glass for sale.
In a similar style, here are some photos of an unmarked, double, straight-side, angular posy vase in pressed glass (white opaque in this case), the sides being embossed with bulrushes and ferns. (Permission for the re-use of these photos on the GMB granted by Kevin Collins). I also have reference photos of an example of this double vase in purple marbled glass, though the marbling is much less ‘ muddy’ than that of Chris’s triple vase.
Fred.