Photo from "Newport Encyclopaedia. Coronation Year and Royal Visit Souvenir 1937."
The fourth Lord Tredegar, Evan Frederic Morgan, born 1893. He inherited the titles baronet, Baron and Viscount and the Tredegar estate in 1934 when his father died. He married twice. In 1928 he married Lois Ina Sturt. She died in Hungary in 1937. Then in 1939 he married Olga Sergeivna Dolgorouky, a Russian princess, while in Singapore. This marriage ended in 1943 when she was granted decree nisi nullity. Thus, on his death in 1949, Evan had no direct descendant. See link below for info about the Lords Tredegar.