Ah, now here's a real English rose. Don't tell Lily Mo Sheen that, though, because she views herself as being strictly Welsh! She gets that from her father, Welsh actor Michael Sheen, so her English mother, actor Kate Beckinsale, apparently lost the battle for national identity. Both parents are practically British acting royalty, so it's no surprise she looks so relaxed in front of a camera.
She looks happy, confident, and casual here, with a natural makeup look and an elegant dress, although you know a lot of work went into making that hair look as effortless as it does. Her parents caused a bit of a social media sensation when they posted celebration photos on social media after Sheen was accepted into her chosen college, so presumably when prom night arrived they were happy to let her have the spotlight to herself for a while.