José Leoncio González de Gregorio y Martí, who died in 2008, was the ex-husband of the late Duchess of Medina Sindonia, Doña Luisa Isabel Álvarez de Toledo y Maura, a woman who could trace her ancestors back to the Duke who led the ill-fated Spanish Armada defeated by Sir Francis Drake in 1588.
A woman has come forward claiming that she is the daughter of Leoncio after a love affair he had with her then underage mother - an employee of his household - four years before he met and married the Duchess.
Rosario Bermudo Muñoz, now 65, claims that she is therefore entitled to a part of his estate, that has been legally inherited by his three legitimate children.
A judge in Madrid on Wednesday ruled that his remains be exhumed so that a paternity test could be conducted using DNA extracted from his corpse.
It is the latest in a long saga of twists and turns to have befallen the aristocratic family of the woman more commonly known as La Duquesa Roja, who caused as much controversy in death as in life.
Rosario Bermudo Muñoz, una mujer de 65 años, ha conseguido que un juez acuerde que se desentierren los restos ... http://t.co/lslhON6N3l— Carolina Blanco (@Nnablanko) June 24, 2015
Dubbed the Red Duchess because she was a life-long opponent of dictator Francisco Franco and openly campaigned for the rights of Spain's poor, she shocked polite society and appalled her own three children when she married her lesbian lover on her deathbed.
It emerged that she had also made out her will to new wife, her German assistant Liliana Maria Dahlmann, in an attempt to defer inheritance to her own children, who had fallen out with her many years earlier in a family feud.
The Duchess had been taken to court by her own children in the 1990s in a bid to prevent her giving away portions of the family estate in Sanlucar in Andalucia, a case which they won.
But Dahlmann will be entitled to live on the family estate until her death and is in charge of the palace archive which contains priceless historical documents and artworks.
The latest legal case launched by Bermudo could see her win an estimated fortune of between €2 - €4 million if indeed she turns out to be the illigetimate daughter of the Duke.
She claims that the duke had a secret relationship with her mother while living in Madrid and that he left her pregnant and penniless to bring up the child alone.
Four years later he married the Doña Luisa and the pair had three children before getting divorced in 2005.
"There is a sizeable legacy at stake here," Fernando Osuna, the lawyer acting for Bermudo told Spanish newspaper El Pais.
He said that previous requests to the known descendents of the Duke to provide a DNA test had been denied. "We wanted to go for the less invasive option but the known children rejected our petition. So, a judge has agreed to the exhumation as the last resort," Osuna explained.