After converting to Catholicism, Princess Alexandra of Hanover, a member of the Royal Family of Monaco, was removed from her distant position in the line of succession for the British Crown.
Princess Alexandra of Hanover is the only child of Prince Ernst August of Hanover and Princess Caroline of Monaco. She was born on July 20, 1999, at Vöcklabruck, in Upper Austria. Alexandra is the only one of Princess Caroline’s four children who bear any royal style or title. Through her father, she is descended from Victoria, Princess Royal, the eldest child of Queen Victoria and Prince Albert.
Princess Alexandra was baptized as a Lutheran in keeping with the rest of the family on 19 September 1999, by the leader of the Evangelical-Lutheran Church of Hanover in a ceremony at her father’s hunting lodge. After deciding to follow her mother Princess Caroline’s footsteps, she was removed from her far place in the British line of succession after becoming Catholic.
The British Monarch is the head of the established Church of England, barring Catholics and any other non-Protestants from ascending to the throne. While the Succession to the Crown Act of 2013 allows heirs to marry Catholics and non-Protestants, they are still banned from becoming sovereign and must be in communion with the Church of England.
While barred from the British throne, Princess Alexandra of Hanover is still 12th in line for the Monegasque throne. You can find the first 17 people in line for the British crown here.