It suggests that, far from discovering America in 1492, Columbus and others in Portugal already knew it was there - and that it blocked any western sea-route to the spice islands. In order to keep the spice trade to itself, Portugal sent Columbus - who was really Salvador Fernandes Zarco, a Portuguese nobleman - to trick the Spanish into thinking that the route to the Indies lay westward.
This theory, the result of 20 years' research by Mascarenhas Barreto, a historian at Lisbon University, is the subject of a book just published in Britain.
Dr Barreto denies that Columbus came from Genoa. The explorer was never heard to speak or write in Italian, only in Portuguese and Spanish. The one person with his name found in Genoese records was a poor wool-carder's son - an unlikely candidate to be the highly educated navigator, who later married a Portuguese noblewoman.
Dr Barreto claims to have unscrambled the mystery of Columbus's signature, which was always in a coded format with a preceding monogram. Dr Barreto says that the signature can be deciphered not only as 'Christopher Colon' ('Columbus' is the anglicised form), but also as 'Salvador Fernandes Zarco'. The monogram, never before unravelled, gives the letters SFZ.
Dr Barreto argues that the only reason for so elaborate a deceit was that Columbus was a secret agent. This explains why, on his return from his 1492 voyage, Columbus first reported to the King of Portugal and not to the King and Queen of Spain. It could also be why he gave Portuguese names to the islands of the Greater and Lesser Antilles. The first he called 'Salvador', after his real first name; the second 'Cuba' after his Portuguese birthplace.
Some historians have long claimed Europeans crossed to America before Columbus. There are reports, for instance, of Portuguese coins in the Caribbean before Columbus first arrived.
His theory has received support from a handful of academics in Portugal and America. But most reject it. 'Tripe,' commented Professor Charles Boxer, eminence grise of British Columbus specialists.
The Portuguese Columbus: Secret Agent of King John II (Macmillan, pounds 18.95).Reuse content