To which court are ambassadors accredited to in the UK?

Ambassadors are accredited to the Court of St James in the UK, which refers to the diplomatic representation to the British monarch. This title originates from St James's Palace, which historically served as the royal residence and the official court. When an ambassador presents their credentials, they do so to the monarch at a ceremony held at the Palace, signifying the formal acceptance of their role in representing their home country.

The other options do not accurately reflect the official title or traditional practices of diplomatic accreditation in the United Kingdom. While the Royal Court and Buckingham Palace are associated with the monarchy, they are not the specific court to which ambassadors are officially accredited. The Court of Westminster also does not pertain to this context of diplomatic relations.