Leopold - son followed Alfred as Duke of Saxe-Coburg and Gotha as Alfred's male heirs die
The Prince Leopold was the eighth child and fourth son of Queen Victoria. He had haemophilia, which led to his death at the age of 30.
Leopold married princess Helene of Waldeck-Pyrmont. Helene was a younger sister of princess Emma, the second (and much younger) wife of King Willem III of the Netherlands. Therefore Queen Wilhelmina of the Netherlands and the children of Leopold and Helene were first cousins.
Leopold and Helene had two children, princess Alice and prince Charles Edward.
On 10 February 1904, Alice married her second cousin once-removed, Prince Alexander of Teck, the brother of Princess Mary, the Princess of Wales (later Queen Mary, consort of George V). She also held the titles of Princess of Saxe-Coburg and Gotha and Duchess in Saxony from birth. After their marriage, Princess Alice was styled HRH Princess Alexander of Teck. When the British Royal Family abandoned all Germanic titles by Letters Patent issued by King George V in June 1917, Prince Alexander of Teck adopted the surname Cambridge, became (briefly) Sir Alexander Cambridge, then the Earl of Athlone, relinquishing the title "Prince of Teck" in the Kingdom of Württemberg and the style Serene Highness.
Alice and Alexander had three children, 1 daughter Lady May and 2 sons Rupert (died in a car crash) and Maurice (died in infancy). Princess Alice was one of the carriers of the gene for haemophilia which arose with Queen Victoria. Princess Alice inherited the gene from her father who himself was a sufferer.
According to the stories Alice had a good relationship with her Dutch relatives. She was godmother to Queen Beatrix of the Netherlands, who is the granddaughter of Queen Wilhelmina of the Netherlands.
Leopold died shortly before the birth of his son Charles Edward. Charles Edward was a first cousin of King George V of Great Britain, Queen Maud of Norway, Grand Duke Ernst Ludwig of Hesse, Empress Alexandra of Russia, Queen Marie of the Romanians, Crown Princess Margaret of Sweden, Queen Victoria Eugenia of Spain, Queen Sophia of the Hellenes, Queen Wilhelmina of the Netherlands, Josias, Hereditary Prince of Waldeck and Pyrmont and German Kaiser Wilhelm II. Such was the interest Wilhelm showed in his young cousin's upbringing that Charles Edward was known as the Emperor's seventh son.
In 1900, 16-year-old Charles Edward inherited the ducal throne of Saxe Coburg and Gotha from is unce prince Alfred. With such strong influences from both his mother and grandmother, he had no choice but to take up the seat of Coburg in order to save that line of Royal blood. The Veste Coburg now became his main royal residence. On 11 October 1905 Charles Edward married Princess Victoria Adelaide of Schleswig-Holstein-Sonderburg-Glücksburg. Together they had five children, 3 sons and 2 daughters. Their eldest daughter Princess Sybilla married Crownprince Gustav Adolf, and are the parents of the current Swedish King Carl XVI Gustaf. After their eldest son prince Johann Leopold renounced his rights (upon a non equal marriage) and their second son prince Hubertus died in WW II, their youngest son prince Friedrich Josias succeeded his father.
Charles Edward joined the Nazi Party in 1935 and became a member of the SA. He also served as a member of the Reichstag representing the Nazi Party from 1937 to 1945. In 1936, Adolf Hitler sent Charles Edward to Britain as president of the Anglo-German Friendship Society. His mission was to improve Anglo-German relations and to explore the possibility of a pact between the two countries. He attended the funeral of his first cousin George V in a uniform of a general of the German army, and sent Hitler encouraging reports about the strength of pro-German sentiment among the British aristocracy. After the Abdication Crisis, he played host to the Duke and Duchess of Windsor, the former King-Emperor and his wife, during their unauthorised private tour of Germany in 1937.
Charles Edward was too old for active service, but his three sons served in the Wehrmacht. After WW II Charles Edward was placed under house arrest at the Veste Coburg because of his Nazi symphaties. He was later imprisoned with other Nazi officials. His sister, Princess Alice, learning of his incarceration, came to Germany with her husband to plead for his release with his American captors. They declined to release him.
In 1946 (August 1949, according to his ODNB entry), he was sentenced by a denazification court, heavily fined and almost bankrupted. Since Gotha was part of Thuringia and therefore in the Soviet occupation zone, the Soviet Army confiscated much of the family's property in Gotha. Coburg had become part of Bavaria in 1920, and the family kept property there and in other parts of Germany and abroad.
He spent the last years of his life in seclusion. In 1953, he travelled to a local cinema to watch the coronation of his cousin's granddaughter, Elizabeth II. Having been evicted by the Allies from the Veste Coburg and his other palaces in 1946, he died in Coburg in his flat in Elsässer Straße on 6 March 1954, as the elder of only two surviving grandsons of Queen Victoria.