Conversation so far:
What was Billy Joel doing musically in 1965?
Joel joined the Echoes, a group that specialized in British Invasion covers.
The Echoes began recording in 1965.
What was the name of the first recording by the Echoes?
Joel played on a demo version of "Leader of the Pack".

Question: Did they do mostly covers?
Self-contained rewrite: Did the Echoes do mostly covers?