From a story on The Common Reader by Henry Oliver headlined “Why I am writing about late bloomers”:

Three sorts of people

Everywhere I go, I tell people I am writing a book about late bloomers. And I get three responses.

Some people ask how old you have to be to be a late bloomer. The short answer is that there is no age. It’s about flourishing after you are expected to. Martina Navratilova was late for high-end tennis in her twenties. Bill Traylor didn’t start drawing until his eighties. Margaret Thatcher was right on time as a fifty-year-old party leader, but a few weeks earlier even her supporters were saying “Oh God, we can’t have Margaret.”