Ang â€” Yes, it is Sowerby. Pattern No. 2566 "Rose Bowl". It came with a matching glass flower holder and, optionally, a 3Â¾" fitting black plinth No. 2616. It dates from the 1930s, and was still being made in the mid 1950s.
Oddly, Sowerby's 1954 trade catalogue describes it as a rose bowl but illustrates it filled with daffodils!Later â€” I have worked it out! The catalogue came out in May, so the the photograph from which the printer produced the block must have been taken March/April time. Too early for roses! Another flower set is shown filled with anemones, again a spring flower.