Brooke was an expert on Thomas Jefferson.
Brooke confided to his nephew that had he'd known his line about plastics in The Graduate (1967) would have become so iconic, as it did, he'd have invested in them. Apparently the market took off in 1968 because of that one remark.
Brooke's favourite comedy was The Kentucky Fried Movie (1977). He loved to laugh, and said it was the funniest film he'd ever seen.
He served in the US military during World War II.
His remains were cremated.