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Nice vase.
The actual manufacturer was John Henry Weatherby & Sons (Ltd) founded in Stoke-on-Trent at Tunstall in 1891 and then at Hanley from 1892 onwards. They used a number of sub-brands and began using the word “ROYAL” in some of the brands during the 1930s, but it was purely a marketing tool to create a sense of prestige. The vase is more recent than that though.
After the Arthur J Wilkinson company of Burslem, Stoke-on-Trent ceased operation in 1964, Weatherby used Wilkinson’s blocks, cases and master moulds to carry on producing almost identical patterns save for the maker mark. I believe that was c.1970. The manufacturing materials were actually purchased by a New York-based firm, Crownford Gifts (hence the ROYAL CROWNFORD IRONSTONE in the mark)
The Crownford China and Crownford Giftware Corp. was a wholesale /distributing / importing company based in New York City operating from 1946 until 2003. Some of their china was American-made, but they widely imported from Staffordshire potteries in England, and also from Italy.
Crownford had previously been supplied with a number of patterns (including, I believe, ‘Calico’, which is most often seen in blue) by Wilkinson and asked Weatherby to continue producing for them using the purchased moulds and transfer-printing plates.