The 17th century’s answer to the WikiLeaks diplomatic cables went online for the first time yesterday.

About 1.2 million pages of British government documents from the Stuart period, including secret reports of espionage and treason sent back from the courts and capitals of Europe, have been scanned and made available on the web.

Among the most intriguing papers is a letter sent to Queen Elizabeth I’s spymaster, Sir Francis Walsingham, containing clandestine intelligence about how “the King of Spaine laboured to get-in with the King of Scotts, and to ruine the Protestant Partie of France”.

Another letter, sent by the Duke of Marlborough in September 1710, records intelligence from a member of the council of state in Brussels about a planned French attack on Scotland.

It notes: “If this proves true the five regiments of the Isle of Wight should be moved northwards and a squadron placed off Dunkirk.”

The manuscripts shine a light on the Stuart era’s paranoia about internal rebellion and foreign invasion. The material forms the final part of the ambitious State Papers Online 1509-1714 project to digitise and index nearly three million documents from the National Archives and the British Library.

Love letters from King Henry VIII to Anne Boleyn are included in the records that have already been released online in the collaboration between educational publisher Gale, part of Cengage Learning, and the National Archives.

The newly-published documents cover Britain’s international relations between 1603 and 1714 through the prisms of marriage alliances, revolutions, wars, treaties, trade and religion.