As an eighteen-year-old, Simon became a volunteer at the newly established Riverside Studios, working closely with Peter Gill and assisting on numerous productions. After leaving Riverside, he became an assistant director at the Royal Court theatre working alongside both Danny Boyle and Max Stafford-Clark. Theatre productions Curtis has worked on include the world premiere of Road, A Lie of the Mind, Roots, Dinner with Friends and The Rise and Fall of Little Voice. In the 1990s, Simon began working as a director for television and his list of credits include Tracey Takes On... for HBO, Twenty Thousand Streets Under the Sky, Cranford and A Short Stay in Switzerland, which was nominated for Best Single Drama at the Royal Television Society Awards and the British Academy Television Awards. Simon’s film directing credits include My Week with Marilyn starring Michelle Williams, Woman in Gold starring Helen Mirren, Downton Abbey: A New Era and its sequel Downton Abbey: The Grand Finale, released in 2025. He and his wife, the actress Elizabeth McGovern, live in Chiswick, West London.