She was the 21st Duchess of Medina Sidonia, Spain's most ancient dukedom whose origins go back to 1297. She was a princess, a marquess and a three-fold Spanish grandee. But from childhood, Luisa Isabel Alvarez de Toledo y Maura kicked against the conventions of her lineage.

She challenged Spain's official history, arguing that Columbus didn't discover America. She was an atheist, a republican and reckoned her 13th-century ancestor Guzman el Bueno, ennobled for fighting the Moors, was a north African whose grandmother was black.

But the Red Duchess – a "title" she never accepted – threw down her most defiant challenge in her final hours.

As she lay dying in her palace in Sanlucar de Barrameda,

Luisa Isabel married in articulo mortis her secretary and companion, Liliana Maria Dahlmann, and left her everything.

Her discreet sexual preferences were known to her family, but the secret lesbian marriage has shaken Spain's proud and ancient aristocracy