Ruth â€” Your vase does not look British to me, but I could easily be wrong.
Confused by "MOP"? The Mt. Washington trade name for air-trap decoration, "Mother-of-Pearl", abbreviated to "MOP", has been turned by some collectors into a generic term for the style. Other American glassworks called it "Plush" and "Pearl Satin", and English glassworks called it "Nacre de Perle", "Verre de Soie", "Broche", "Sateen", and "Tartan". See Hajdamach p309 for more details.
Walsh Mother-of-Pearl was a very thin layer of white opal cased in crystal, green, or straw opal and iridised â€” with no hint of air-trap. The crystal cased version actually looks like real Mother-of-Pearl. Walsh also made air-trap glass under the names "Broche" and "Sateen". You can guess what's coming â€” I've been waiting over a year for the opportunity â€” grateful thanks Ruth. Theoretically Walsh could have combined their Mother-of-Pearl with air-trap, producing what collectors today would term "Walsh Walsh MOP MOP".