Mark — Your little posy vase is a Davidson M.T.1, launched by Davidson in 1961, possibly from an old Matthew Turnbull mould, which may explain the strange pattern number. See
here for more details. As you will see it optionally came with a Davidson 312 plinth, not the Sowerby 2530, so definitely a marriage. Don't be too hasty to condemn your supplier as I am sure that at the time both wholesalers and retailers would have done likewise to make any odds and ends saleable.
We're still no further in working out what the 2530 was designed for, see
here.
Bernard C.