The possible connections which I found in the Elliott (ref  70) book between d’Olivares (Gaspar de Guzman) and the Duque de Losada were:

1.       In 1620 Olivares was helped get access to the future King Philip 4 by Antonio de Losa whose name suggests old de Losada nobility

2.       Andres de Losada y Prada was secretary of state for northern European affairs but when he died in 1627 his job was combined (by Olivares) with the corresponding Italian job to create a higher post

3.       We already knew that the (nominal) maternal grandfather of the Duque de Losada was Martin de Saavedra y Guzman and that his maternal grandmother was Luisa de Guevara

4.       As we knew the nominal father of the Duque de Losada was Sancho Fernandez de Miranda y Frelles

5.       Olivares was ‘sumiller de corps’ for Phillip IV like the Duque de Losada became for Carlos 3. Olivares later assumed the superior palace role of ‘camarero mayor’ or grand chamberlain. It is not clear that the Duque got the same promotion for the superior role fell into abeyance (ref 159). Olivares succeeded Baltazar de Zuniga (the Guzmans and Zunigas were allied families) who succeeded the Duke of Lerma. In the 1720s another Baltazar de Zuniga became sumiller de corps. Later more Guzmans assumed the role, but in 1759 the Duque de Losada succeeded a Zuniga when Charles 3 became King.

6.       Olivares early on was keen to be ‘covered’ in the presence of the King ie to be a grandee of the first rank – he succeeded like the Duque de Losada in achieving this rank

7.       Olivares – with some New Christian ancestry himself – did not shrink from using the Portuguese New Christian financiers, or from being advised by Manuel Lopes Pereira, nor from appointing Jeronimo de Villanueva – of probable Jewish origin from a family of Aragonese royal officials. Villanueva had trepidations about accepting membership of the military Order of Calatrava because of the likely close inspection of his ancestry.

8.       (Perhaps more relevant to the English Lousada Dukes) Count Henri van den Bergh proved to be an unreliable ally of the Spanish in the Spanish Netherlands in the wars with the Dutch and French

9.       Diego de Saavedra Fajardo had his career developed by Olivares

10.   Manuel Botelo de Sossa was a Portuguese in the Hague who warned Olivares of trouble in Andalucia (caused by Olivares’ own Medina Sidonia family!). Note the similarity of name with the Lamego representative in Jamaica around 1620 (ie Serrano Manuel Botello).

11.   Luiza de Guzman became Queen of Portugal after her husband the Duke of Braganza’s cheeky coup. The 1633 marriage and especially the 1640 coup was a source of shame to Olivares who wanted her expunged from family history. His mixed feelings about her perhaps arose in part from the fact that her grandfather was the Duke of Lerma - who was displaced by Don Baltazar de Zuniga and his protege and nephew Olivares.

12.   Further Guzman relatives came under grave suspicion of treachery at this time for closeness with the new Portuguese regime.

13.   Ana de Guevara had been the King’s nurse

14.   When Olivares became certain he would have no descendants, he had a bastard son Enrique elevated. Enrique had been placed with Guzman family members to be brought up as theirs. He was the result of a 1612 encounter with a high-placed lady at court.

15.   The Count de Miranda was ‘another of Olivares’ creatures’

16.   Olivares was succeeded by his nephew Luis de Haro; the Duque de Losada was similarly succeeded

17.   Olivares had a brother-in-law Monterrey who had estates in Galicia – origin of the de Losada nobility