Conversation so far:
What did the Fairport Convention do in 1986?
In 1986 the band began a hectic schedule of performing in Britain and the World and prepared material for a new album.
Which new album did Fairport Convention prepare for in 1986?
The new album was the all-instrumental Expletive Delighted! (1986).
Was the album Expletive Delighted! A hit?

Question: what was their biggest concert?
Self-contained rewrite: What was Fairport Convention’s biggest concert?