Simplify the following text for a Grade 8 native English-speaking person.
Original: The big rise to fame came in 1961 , playing the role of John Steed , British TV Series The Avengers , originally in the series he was co-star of Ian Hendry , but Hendry left the show , to end the first season .
Simplified: The series was conceived as a vehicle for Ian Hendry who played the lead role . Steed was the secondary character , the assistant to Hendry 's character .