The baby names Jolyon and Nyree both debuted in the U.S. baby name data 1970:
| Boys named Jolyon | Girls named Nyree | |
| 1973 | 5 | 157† |
| 1972 | 5 | 26 |
| 1971 | . | 7 |
| 1970 | 9* | 10* |
| 1969 | . | . |
| 1968 | . | . |
They both came from the same source: The Forsyte Saga, a 26-part, Emmy-nominated BBC miniseries that followed several generations of the nouveau riche Forsyte family of London from the 1870s to the 1930s.
It first aired on U.S. public television from October of 1969 to March of 1970. (It originally aired in the UK during the first half of 1967.)
The Forsyte Saga was based on a book series of the same name written during the early 1900s by Nobel Prize-winning English author John Galsworthy.
At the start of the TV miniseries, the Forsyte family was nominally headed by Jolyon Forsyte (played by Joseph O’Conor), who had a son also named Jolyon (played by Kenneth More). The father was called “Old Jolyon” and the son was called “Young Jolyon.” Their shared first name was pronounced joe-leon.
Later on in the series, Young Jolyon had a son named Jolyon, nicknamed “Jolly.” Later still, with a different woman, he had another son named Jolyon, this one nicknamed “Jon.”
The name Jolyon is usually said to be a medieval form of Julian, but it could also come from a byname that meant “jolly Jan.”
Another character in the series was Irene Heron (played by Nyree Dawn Porter). She was introduced in the second episode, and she married into the Forsyte family during the time that elapsed between the third and fourth episodes.
That initial marriage didn’t last, though, and Irene ultimately ended up with Young Jolyon, becoming the mother of Jon.
New Zealand-born British actress Nyree Dawn Porter was named Ngaire at birth. For her stage name, she used the Anglicized spelling of her Maori first name.
The name Ngaire (pronounced NY-ree) is based on the Maori word ngaere, which may refer to a swamp or wetland.
(The usage of Nyree swelled in the mid-1970s. This could be due to the British show The Protectors (1972-1974), which co-starred Porter and also aired on U.S. television. The name of Nyree’s character, Contessa, more than doubled in usage from 1972 to 1973.)
Sources: The Forsyte Saga – IMDb, Nyree Dawn Porter – Wikipedia, Namehunt: Jolyon | Dictionary of Medieval Names from European Sources, ngaere – Maori Dictionary, SSA