I remember WB prints being on sale to collectors "back in the day"; maybe there was an ad in FILM FAN MONTHLY or some mag like that. UA also put some of the top oldies back in movie theaters during that era's "camp craze." According to a 1970 VARIETY article:

<< UA’s ownership of old WB pics stems from WB's sellout to Eliot Hyman, than in business under name of Associated Artists Prods. Hyman sold AAP to UA, then formed Seven Arts. UA renamed AAP United Artists Associated. Firm’s ownership of pre-’48 RKO features followed a slightly longer trail starting from original sale of Matty Fox. <