For a while in the late 1960s Gibb was in a relationship with Kaffe Fassett, who remained a close friend and colleague to the end.
He received a scholarship to the School of the Museum of Fine Arts, Boston at the age of 19, but shortly left school to paint in London and moved there to live in 1964.
Beatrix Miller of Vogue selected one of Gibb's designs for Baccarat, a pleated tartan skirt and printed blouse worn with a Kaffe Fassett knitted waistcoat, as the 1970 Dress of the Year.