However, in March 1970, Barclay left Fanny to be a member of Joe Cocker's hastily organized Mad Dogs & Englishmen seven-week tour of the USA, but rejoined Fanny reluctantly after that tour concluded in May 1970. Their first big gig as Fanny was at the Santa Monica Civic Auditorium with the Kinks and Procol Harum. Fanny was the first all-female rock band to release an album with a major label, and they eventually released five albums and achieved two top-40 singles on the "Billboard" Hot 100. The band has long been considered pioneers and are highly respected by later all-women rock groups like The Go-Go's and The Runaways. In 1999 Fanny fan David Bowie said that Fanny was "extraordinary... they're as important as anybody else who's ever been, ever; it just wasn't their time." In this period, Millington and the other members of Fanny worked as session musicians, most notably in June 1971 on Barbra Streisand's album "Barbra Joan Streisand" that was produced by Perry. They appeared on national TV programs, including "The Tonight Show" with Johnny Carson, "The Midnight Special", "Don Kirshner Presents", and the "Sonny & Cher Comedy Hour". Additionally, they appeared on "The Kenny Rogers Show" in Canada, the BBC's" Old Grey Whistle Test", and Germany's "Beat-Club". However, because of tensions within the band, including frequent disagreements with Barclay over their conflicting musical preferences, and soon after having a nervous breakdown "because of the pressures of touring, recording, coping with success, maintaining success, and maintaining a certain image in the boy-defined rock world", Millington left Fanny after their fourth album "Mother's Pride" was released in February 1973. Millington was replaced as lead guitarist by Patti Quatro (born Patricia Helen Quatrocchio on March 10, 1948, in Detroit, Michigan), sister of Suzi Quatro, and former member of all-female bands The Pleasure Seekers and Cradle in March 1974. Thirty years after her breakdown, Millington summarized: "Instead of carrying it all, I just fell apart." In 2008, Millington revealed in an interview:  I was just so intent on my mission to do music come hell or high water that I was missing a lot of the subtleties of life — which is why I'd left Hollywood. I had intuited that I was in trouble and I had to leave — which was very difficult.