Table: spearhead_episodes
Columns: episode
original_air_date_uk
episode_title
director
writer
cast

Question: What is the original air date of the episode "Another Happy Day"?
SQL: SELECT "original_air_date_uk" FROM spearhead_episodes WHERE "episode_title" = 'Another Happy Day'

Question: What is the title of the episode that aired on 13 august 1981?
SQL: SELECT "episode_title" FROM spearhead_episodes WHERE "original_air_date_uk" = '13 August 1981'

Question: What is the original air date of episode 3-02?
SQL: SELECT "original_air_date_uk" FROM spearhead_episodes WHERE "episode" = '3-02'

Question: Who are the cast members of episode 3-04?
SQL: SELECT "cast" FROM spearhead_episodes WHERE "episode" = '3-04'