Lady Alice St Clair-Erskine (born 1989), also known by her stage name Alice St Clair, is an English actress known for playing Kate Middleton in William & Catherine: A Royal Romance and Flora Marshall in The Crimson Field.

St Clair was born in 1989, the eldest daughter of Peter St Clair-Erskine, 7th Earl of Rosslyn and Helen Watters. She was educated at Heathfield St Mary's School and Bedales School. St Clair is also a poet who works under the name of Alan Moon and a voice-over artist whose work includes Air B and B, BBC Radio 4's Homefront and BBC Radio 3's Words and Music.