Contrary to what has been posted elsewhere, there is no truth to the story that Grand Duchess Maria of Russia and Prince Michael of Kent were an item when she was at Oxford in the mid-70s. She had no real contact with members of the British royal family (even though her own grandmother was a British princess) although she did once have tea with Queen Elizabeth II at Buckingham Palace. But that was it. Prince Michael married Baroness Marie Christine von Reibnitz in June 1978, and they had known each other for several years. Moreover, Michael was always been drawn to svelte tall women. Grand Duchess Maria is an intelligent and witty lady, but svelte is not in her DNA.
There is of course a family connection to the Kents. Michael's mother, Princess Marina of Greece and Denmark, was the daughter of Prince Nicholas of Greece and Denmark and Grand Duchess Helen Wladimirovna of Russia. Helen's brother, Grand Duke Kirill, who became head of the Imperial Family in July 1918, was married to Princess Victoria Melita of Edinburgh, Princess of Saxe-Coburg and Gotha (granddaughter of Queen Victoria). Kirill and Ducky had three children: Maria (who married the Prince of Leiningen), Kira (married to Prince Louis Ferdinand of Prussia, de jure German Emperor and king of Prussia) and Wladimir, who succeeded his father as head of the Imperial Family.
Grand Duchess Kira was one of Marina's bridesmaids in 1934 when she married the duke of Kent.
Grand Duke Wladimir was Grand Duchess Maria's father. Michael and Maria are second cousins, as their parents are first cousins.
Helen-Marina-Michael and Kirill-Wladimir-Maria.
It is entirely possible that the Kent siblings made contact with the their Russian cousin during her short stay in the UK, but Kirill's family have largely been excluded from Kent family celebrations since Marina's wedding.
Family isn't always based on your genealogical connections.