Duchess of Alba's family blocked from auctioning Christopher Columbus' letter to his son

The Madrid judge has rejected an appeal by the Casa de Alba Foundation against Spain's ministry of culture which had prevented the Duchess' family from putting the missive up for bidding.

Colombus' letter, valued at €21 million, is dated April 29, 1498 and forms part of a collection of eight written by the admiral who discovered the Americas between then and 1501 held by the Alba house, although the other seven are addressed to Friar Gaspar de Gorricio.

The Alba house argued that the letter to Diego Columbus was written from Sevilla rather than from the 'new world', the content was mainly about 'domestic matters' and – as a Christie's report states - it is chronologically separated from all the other known letters between father and son.

These factors mean it is 'of little historical value', says the Casa de Alba Foundation, a factor backed up by the auction house.

But the ministry of culture says the letter forms part of Columbus' archive ceded to the State in 1929 by the Duke and Duchess of Veragua.

The family became a member of the Alba dynasty through the marriage of the eighth Duchess of Veragua, who was also the Countess of Gesves, to Jacobo Fitz-James Stuart, second Duke of Berwick, in the 18^th century.

For several centuries, the archive has been in two different parts, since the Duchess of Veragua and the Duke of Berwick eventually parted company, which is how the eight letters – including the one to Columbus' son Diego – ended up in the hands of the Casa de Alba Foundation.

The ministry insists it is a unique part of Spanish heritage and should not therefore be sold – especially as it is one of the earliest letters between Columbus and his son which remains in existence today.

Cayetana Fitz-James Stuart, the last Duchess of Alba who passed away at the end of 2014, set up the foundation in May 1975 and ran it until her death five months ago.

Among the heritage it owns, which is now managed by Cayetana's children, are the Palace of Liria, the Palace of Monterrey and the family's castle in Alba de Tormes, plus a huge private art collection including originals by Picasso, El Greco, Goya, Murillo, Velázquez, Rénoir, Van Dyck, Veronés, Fra Angélico, Mengs, Van Loo and Tiziano, among others.

Despite the immense value of the Alba family's art and property, it cannot be freely sold as it is subject to national legislation covering cultural foundations and historic and artistic heritage.

Photograph: Christopher Columbus, or Cristóbal Colón – his real name before translation from Spanish to English – painted in 1828 by Rafael Tejedo