The Scarlet Pimpinel

A late-18th-century "double life" dude who pretended to be just a faceless British aristocrat, but in reality would secretly go around treating people's illnesses with herbal remedies, rather than the mainstream "drugs and surgery" methods.

Baroness Orczy always looked quite good, so perhaps she herself was treated by The Scarlet Pimpinel; maybe she even wrote the book about him as a gratitude gesture for his helping to keep her in good health.