Born to a well-connected family of gentry, Walsingham attended Cambridge University and travelled in continental Europe before embarking on a career in law at the age of twenty.

Walsingham rose from relative obscurity to become one of the small coterie who directed the Elizabethan state, overseeing foreign, domestic and religious policy.

He oversaw operations that penetrated Spanish military preparation, gathered intelligence from across Europe, disrupted a range of plots against Elizabeth and secured the execution of Mary, Queen of Scots.

Walsingham returned to England and through the support of one of his fellow former exiles, Francis Russell, 2nd Earl of Bedford, he was elected to Elizabeth's first parliament as the member for Bossiney, Cornwall, in 1559.

[15] In January 1562 he married Anne, daughter of Sir George Barne, Lord Mayor of London in 1552–3, and widow of wine merchant Alexander Carleill.

[21] He is credited with writing propaganda decrying a conspiratorial marriage between Mary and Thomas Howard, 4th Duke of Norfolk,[b] and Roberto di Ridolfi, after whom the plot was named, was interrogated at Walsingham's house.

When Catholic opposition to this course in France resulted in the death of Huguenot leader Gaspard de Coligny and the St. Bartholomew's Day massacre, Walsingham's house in Paris became a temporary sanctuary for Protestant refugees, including Philip Sidney.

[37] He was knighted on 1 December 1577,[38] and held the sinecure posts of Recorder of Colchester, custos rotulorum of Hampshire, and High Steward of Salisbury, Ipswich and Winchester.

[40] The duties of the principal secretary were not defined formally,[41] but as he handled all royal correspondence and determined the agenda of council meetings, he could wield great influence in all matters of policy and in every field of government, both foreign and domestic.

[42] During his term of office, Walsingham supported the use of England's maritime power to open new trade routes and explore the New World, and was at the heart of international affairs.

He was involved directly with English policy towards Spain, the Netherlands, Scotland, Ireland and France, and embarked on several diplomatic missions to neighbouring European states.

[43] He supported the attempts of John Davis and Martin Frobisher to discover the Northwest Passage and exploit the mineral resources of Labrador, and encouraged Humphrey Gilbert's exploration of Newfoundland.

[51] Between 1578 and 1581 the Queen resurrected attempts to negotiate a marriage with Henry III's youngest brother, the Duke of Alençon, who had put himself forward as a protector of the Huguenots and a potential leader of the Dutch.

[59][c] These were years of tension in policy towards France, with Walsingham sceptical of the unpredictable Henry III and distrustful of the English ambassador in Paris, Edward Stafford.

[64] After the collapse of the Raid of Ruthven, another initiative to secure a pro-English government in Scotland,[65] Walsingham reluctantly visited the Scottish court in August 1583, knowing that his diplomatic mission was unlikely to succeed.

[67] Walsingham replied with a discourse on the topic that "young princes were many times carried into great errors upon an opinion of the absoluteness of their royal authority and do not consider, that when they transgress the bounds and limits of the law, they leave to be kings and become tyrants.

[76] As part of the marriage agreement, Walsingham agreed to pay £1,500 of Sidney's debts and gave his daughter and son-in-law the use of his manor at Barn Elms in Surrey.

[82] Walsingham could never forget the atrocities against Protestants he had witnessed in France during the Bartholomew's Day massacre and believed a similar slaughter would occur in England in the event of a Catholic resurgence.

[86] Walsingham's staff in England included the cryptographer Thomas Phelippes, who was an expert in forgery and deciphering letters, and Arthur Gregory, who was skilled at breaking and repairing seals without detection.

[87] In May 1582, letters from the Spanish ambassador in England, Bernardino de Mendoza, to contacts in Scotland were found on a messenger by Sir John Forster, who forwarded them to Walsingham.

[96] After the assassination in mid-1584 of William the Silent, the leader of the Dutch revolt against Spain, English military intervention in the Low Countries was agreed in the Treaties of Nonsuch of 1585.

[101] Walsingham instructed Paulet to open, read and pass to Mary unsealed any letters that she received, and to block any potential route for clandestine correspondence.

[102] In a successful attempt to entrap her, Walsingham arranged a single exception: a covert means for Mary's letters to be smuggled in and out of Chartley in a beer keg.

"[113] Walsingham made arrangements for Mary's execution; Elizabeth signed the warrant on 1 February 1587 and entrusted it to William Davison, who had been appointed as junior Secretary of State in late September 1586.

[118] Walsingham worked to prepare England for a potential war with Spain, in particular by supervising the substantial rebuilding of Dover Harbour,[119] and encouraging a more aggressive strategy.

[125] While foreign intelligence was a normal part of the principal secretary's activities, Walsingham brought to it flair and ambition, and large sums of his own money.

[126] He cast his net more widely than others had done previously: expanding and exploiting links across the continent as well as in Constantinople and Algiers,[125] and building and inserting contacts among Catholic exiles.

His primary residences, apart from the court, were in Seething Lane by the Tower of London (now the site of a Victorian office building called Walsingham House), at Barn Elms in Surrey and at Odiham in Hampshire.

[145] He was part of a Protestant intelligentsia that included Philip Sidney, Edmund Spenser and John Dee: men who promoted an expansionist and nationalist English Renaissance.

Charles Nicholl examined (and rejected) such theories in The Reckoning: The Murder of Christopher Marlowe (1992), which was used as a source by Anthony Burgess for his novel A Dead Man in Deptford (1993).