I dispute your words that the island is a "rather sad place". It is a place full of people living in a remote island but the place is a warm and vibrant community full of history. Not just the history of the mutiny, but the history of the Tahitian ancestry pre-mutiny. They have a local government where local laws are enacted but as you say, they are British ruled due to a an encounter in the 1838 of a British ship where the Pitcairners asked for some laws to be drafted. Many administration aspects are managed from New Zealand for convenience but it is not administered by New Zealand. The High Commissioner in Auckland is a represents the UK.