Wyvern was an English brand from the late 19th Century until the early 1960’s. They made a wide variety of pens, including brands for other companies, and were known for excellent nibs. Perhaps their best known model is the Perfect, one of which is in my collection (link). Other models were the Deluxe, the Envoy, and the Ambassador. Their heyday was before and just after WWII, when their pens were in very attractive marbled celluloids.