Caroline is related to the Vesteys who are close to the Queen (horses, you know) but the Vesteys would have been considered arriviste by the 18th century aristos as I think they got their title through trade, ie grocery stores. I don't think that makes her royalty, ferchrissake. Also, if you're blue-blue-blood, you never claim how close you are to royalty because they're all Germans. And most of the higher-ranked aristos (dukes, particularly) are offspring of royalty on the wrong side of the blanket.
Annabelle was a fixture in Tatler, mainly because she used to be married to Nat Rothschild. Noelle showed up only when she was engaged to Matthew Mellon after he and Tamara (Jimmy Choo co-founder) Yeardye split up. I don't know if I would have called Annabelle one of McQueen's muses (a term as overused and misused as "diva"). She was definitely friends with him, but who in London wasn't?
The Americans - I've never seen or heard of them ever, including the Earl of Sandwich's wife. She's not on the regular Tatler society scene (mostly aristos who all went to school together and never stopped partying with the exact same people into perpetuity). Apparently she's on the made-for-TV London party scene, huh?