The NKVD then sent him to China. There he taught English at Saint John's University, Shanghai to spy on a Trotskyite whose arguments in fact began to convince him. Crook proceeded to Chengdu and was there when it was bombed by the Japanese. While there he met his future wife, Isabel Brown, daughter of Canadian missionaries."Spain to China – Agent to Educator (1938–41)," Crook, Hampstead Heath to Tiananamen
