Conversation so far:
What is important about the Mike Batt era?
With their star now conspicuously ascendant, Steeleye Span brought in producer Mike Batt to work on their eighth album, All Around My Hat.
How well did the band Steeleye Span perform when they brought in the producer Mike Batt?
After Mike Batt joined, Steeleye Span released All Around My Hat, and the title track was their biggest success.

Question: Around what dates did this happen?
Self-contained rewrite: Around what dates did Mike Batt  join Steeleye Span?