Mainly in-letters to the Secretary of State from the English (later British) ambassadors, envoys and resident ministers appointed to Spain. Most of the letters are dated at Madrid (or The Escorial), though Seville was a popular royal residence. Despatches from the consuls (eg at Madrid, Alicante, Barcelona, Bilbao, Cadiz, Cartagena, Corunna, Malaga, San Sebastian, Seville and Tenerife in the Canary Islands) are also in the series, as well as a number of letters from the consulates at Lisbon and Faro, and a few for that at Oporto (all three cities in Portugal). A few papers are from Gibraltar, captured from Spain in 1704. Many draft replies by the Secretary of State are also in the series, and a number of petitions, royal letters, and transcripts of intercepted despatches.
The series includes correspondence with the commissioners appointed in 1730 to enquire into the abuses and hardships suffered by subjects of King George II and the difficulties that British trade lay under in the dominions of Spain. Their entry book is also in the series, as well as a number of papers relating to military and naval matters.