Grand Duchess Elena Vladimirovna of Russia (January 17, 1882 to March 13, 1957) was born into Russian aristocracy: she was a first cousin of Nicholas II. She married into the Greek royal family. Here a little background is necessary for today's story.
Elena, or Helen, was referred to as Princess Nicholas of Greece. That particular formulation pointed to the fact her husband was the son of the King of Greece, but Helen was not the daughter of a king, so her princess title reflected her husband's status.
The Greek royal family at the time consisted of the children of George I and Queen Olga. That would be, besides their daughters, Crown Prince Constantine, Prince Andrew, Prince George, and, besides Prince Nicholas, Prince Christopher, and various spouses.
Prince Christopher (August 10, 1888 to January 21, 1940) was called "Christo" in the family, We rely on a biography of Alice, the wife of Prince Andrew, titled, Alice Princess Andrew of Greece by Hugo Vickers (2004) for the rest of this post.
"Christo" is described as "a benign and harmless soul", who dabbled in the occult, (automatic writing, ghosts) and married a "very rich woman," an American heiress, Nancy Leeds. After World War I the family was often in exile.
According to Vickers, the money Christo was delivering to the Red Cross in Greece, a huge amount, explains why he was not monitored as closely as others in the family, during the turbulent times of the 1920s. Which leads us to the fact Christo was able to visit the royal country home, Tatoi, fifteen miles from Athens. Even though he had to make "a precipitate departure Christo retrieved his securities and Princess Nicholas's prize possessions, her substantial collection of jewels and her Persian cat."
This is a quote from page 166 in Vickers' book.