According to her Wikipedia article, Claire Clairmont was Mary Shelly's (click here to see Mary Shelly's most famous product) stepsister and she bore George Gordon, Lord Byron's daughter Allegra, and may have had an affair with Percy Bysshe Shelly.
From bbc.co.
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This portrait shows the Romantic era reincarnation of the ruff and partlet that rests upon what appears to be a pleated bodice.
Keywords: 1819, Curran, Claire Clairmont, Gordon family, vurly coiffure, high neckline, ruff, patlet, square neckline, upper puffed sleeves