#698s Vagrant was built in 1910 for Harold Vanderbilt. In early 1914 he sold her to Hendon Chubb after the second "big" Vagrant (#719s) had been built for him in 1913. Chubb renamed her Queen Mab and raced her very successfully, winning the Astor Cup in 1915. He kept her for only a few years before he sold her to Reginald C. Robbins of Marblehead, who in 1921 sold her on to Nathaniel P. Ayer of Boston. During the winter of 1921/22 she was converted to a staysail schooner by HMCo, becoming what L. Francis Herreshoff believed to have been the first American schooner with track and slides on the luff of her mainsail. Horace Binney became her new owner in 1926 and kept her until 1936 when she was sold W. A. W. Stewart who had just become commodore of the N.Y.Y. C. Under Stewart's ownership she won the Astor Cup twice, in 1936 and 1937, and the Commodore's Cup in 1938. After that Queen Mab quickly went through several owners, including the Federal Insurance Company in 1939, Summer Pingree in 1941, and James B. Crockett in 1947. In 1947 she was bought by Glenn Myers of Los Angeles and was moved to the West Coast. From 1950 to 1954 she was owned by Stanley Runyan, still homeported in L.A. Then came the long period of 21 years of ownership by Phyllis B. Brunson and Robert L Pringle that has been alluded to above. During these years Queen Mab was raced a lot, including nine consecutive Los Angeles to Honolulu Transpac races. By the late 1970s Queen Mab was doing charter work in the Carribean. There she was "discovered" by the Dutchman Hans Lammers, who acquired her in 1976 and gave her back her old name Vagrant. She continued to charter but lost both her masts in a severe gust in 1984 when she was bought by British America's Cup challenger Peter de Savary who, over the course of two years, had her restored in Antigua back to gaff rig (done by Spencer Rigging of West Cowes, Isle of Wight). De Savary brought her to Europe and kept her until 1991 when she was acquired by her current Japanese owners.
I hope this answers some of the above questions.
Anyone interested in Herreshoff schooners should try to at least get a look at Taglang, Jacques. Mariette and the Herreshoff Schooners. Two vols. Eynesse, 2010. It's really good!