Elizabeth's socioeconomic background

I was hoping to learn more of her history. Blethyn generally plays working-class characters, and Elizabeth doesn't sound as if she was raised in Mayfair, but I know it's extremely expensive to live in the Channel Islands, and particularly to own a large, imposing house, as hers is. Of course, that home may have passed down through multiple generations. Her late husband served in the Royal Navy, but who knows which rank he held. Obviously, she doesn't have to work, and if her daughter was raised on the island, with money, it wouldn't be unusual for her to escape to a more cosmopolitan place and embrace a lifestyle alien to her. A bit of rebellion.