Andrew H Robertson was 18 at the time he made Cement Garden. Interesting that Andrew Birkin “wanted” 13 year old Ben initially. I think that was a cover for him to handpick some children that David Birkin pointed out. Not for the movie at all. Ned Birkin was in the movie and so was Charlotte Gainsbourg. The only other male child in movie was 6 years old, way too young for Ben to play.