Complex sentence: She made her London stage debut in February 1937 and appeared in over a hundred British films in supporting roles, mostly comedy character parts such as slightly eccentric mothers, grannies, landladies and servants.
Split into simpler sentences: She made her London stage debut in February 1937. She went on to appear in over a hundred British films in supporting roles, mostly comedy character parts such as slightly eccentric mothers, grannies, landladies and servants.