Table schema:
CREATE TABLE table_name_15 (actual_title VARCHAR, writer VARCHAR, artist VARCHAR, issue VARCHAR)

Question: What was the actual title of the show that had an issue number less than 508, was written by Desmond Devlin, and for which Tom Richmond was the artist?
SQL: SELECT actual_title FROM table_name_15 WHERE artist = "tom richmond" AND issue < 508 AND writer = "desmond devlin"