Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
--------
Question: Who played Lionel Hardcastle in the TV series 'As Time Goes By'?

Answer: as time goes by


Question: Which legal drama starring Martin Shaw ran for six series on BBC TV from 2001?

Answer: martin shaw


Question: At which racecourse would you watch both the 'Oaks' and the 'Derby'?

Answer:
epsom derby