The photograph has no visible copyright markings. Photograph is not dated, but Howard was with MGM only in 1939, during production of Gone with the Wind. He returned to England in August 1939, before the film's release.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.