He was also, shortly after birth in 1914, made a British prince by King George V of the United Kingdom,[2] and was heir to the titles Duke of Cumberland and Teviotdale and Earl of Armagh.

The christening of Ernst August in the summer of 1914 was the last great gathering of European monarchs before the start of World War I.

[4] In 1938 his sister, Princess Frederica had married the later King Paul I of the Hellenes and in 1946 his younger brother Prince George William married Princess Sophie of Greece and Denmark, thus becoming the brother-in-law of Prince Philip, Duke of Edinburgh and Queen Elizabeth II of the United Kingdom.

Ernest Augustus was himself an heir to the British titles of Prince of Great Britain and Ireland, recognised ad personam for Ernst August's father as well as for him and his siblings by King George V of the United Kingdom on 17 June 1914,[5] Duke of Cumberland and Teviotdale, Earl of Armagh, which however were all suspended under the Titles Deprivation Act 1917.

In addition to being a German, he also held British nationality, after successfully claiming it under the Sophia Naturalization Act 1705 in the case of Attorney-General v. Prince Ernest Augustus of Hanover.

Ernest Augustus however did not marry Maria Anna because his parents would not have approved, since she was considered of inadequate birth and was also a divorcée, and the marriage would have made his younger brother Prince George William heir to the headship of the House of Hanover.

The child, christened Christian Ernst August Hubertus, Freiherr von Humboldt-Dachroeden, was born in 1943 and is currently a bank consultant.

[9] The wedding was attended by many important royal figures, including his sister Queen Frederica and her husband King Paul of Greece, and the heads of the houses of Saxony, Hesse, Mecklenburg, Oldenburg, and Baden.

He died at Schulenburg, Pattensen, Lower Saxony, Germany, aged 73, and was buried next to his first wife on a round bastion of Marienburg Castle (Hanover).