When were the Cayman Islands officially declared a part of the British Commonwealth?

The Cayman Islands were officially declared a part of the British Commonwealth in 1670 as a consequence of the Treaty of Madrid, which came in the aftermath of the capture of Jamaica from Spain. This treaty established British sovereignty over Jamaica and extended that claim to the Cayman Islands, which had been settled shortly before. This link to Jamaica solidified the Cayman Islands' status within the British Empire, aligning them closely with British colonial governance and influence. The establishment of the islands as a dependency of Jamaica underlines their integration into the Commonwealth framework during that period.

The other dates mentioned do not correspond to events that marked the formal declaration of the Cayman Islands’ status within the British Commonwealth, which is specific to the treaties and colonial arrangements following the capture of Jamaica.