Prince George and his brother The Prince of Wales joined an elite 1920s group.
They earned the moniker "Bright Young Things". The media labeled them as bohemians, aristocrats, and socialites.
I think it would be "some Bohemians, aristocrats and socialites were labeled Bright Young Things." It was a broadly applied label to a large, amorphous group of people, not with specific "membership."
Interestingly, Wilsford Manor is for sale. It was the long-time home of the Brightest of the Bright Young Things, Hon Stephen Tennant. I haven't usually seen the prince and duke included as BYT, though they were photographed at night clubs once in a while.