He was soon recruited by Francis Walsingham to act as a spy until 1583, by which time he felt his consorting with French Catholics was compromising his religious integrity.
[2] Fowler's letters to Walsingham mention his widowed mother's concern at his role and intrigues in London and her moneylending activities, and information he obtained in January 1583 from the exiled Scottish Duke of Lennox.
[3] Coded letters mentioning Mary's distrust of Fowler were discovered in the Bibliothèque nationale de France and deciphered in 2023.
In September 1584, he met the German traveller Lupold von Wedel in Edinburgh and told him that he been teaching King James the art of memory.
[13] Fowler returned to Scotland before James VI, and planned to rejoin the royal party in Denmark in April 1590.
[14] The English diplomat in Edinburgh Robert Bowes reported to Burghley and Walsingham that Fowler had obtained two letters in cipher, one to the Earl of Erroll and the other mysteriously addressed to "Assuerus the Painter".
Fowler gave the letters to the Provost of Edinburgh, Sir John Arnot to show them to the Privy Council.
[16] At this time Giacomo Castelvetro, an Italian writer, served James VI and Anne of Denmark as a language tutor and secretary.
He drew out a Latin acrostic poem for a manuscript of Fowler's discourse on the history of mathematics titled 'Methodi, sive compendii mathematici'.
[19] At the feast following the baptism at Stirling Castle, a "Moore or Blackamoor"[20][21] dragged a pageant cart with six ladies holding desserts towards the dais or high table in the great hall.
George Nicholson mentioned in March that Fowler needed encouragement and reassurance by a letter from the Secretary, Sir Robert Cecil.
[28] Shortly after the Union of the Crowns, on 5 April 1603, before joining the king in London, Fowler wrote a note describing the devices or emblems embroidered on a bed belonging to Mary, Queen of Scots, which seems to have been in place in a chamber at Holyrood Palace with matching chairs.
[29] On 28 April he wrote to Robert Cecil from Edinburgh, enclosing royal letters (from Anne of Denmark) and offering his service.
[30] At the Union of Crowns, Fowler travelled south with Anne of Denmark and met the Earl of Shewsbury at Worksop Manor.
[31] Fowler was confirmed as secretary and Master of Requests to Anne of Denmark, and joined the council administering her new English jointure lands.
[33] In September 1603, he met Arbella Stuart at Woodstock Palace, and wrote two sonnets, one addressed to her, and the Upon a Horologe of the Clock at Loseley which contains a partial anagram of her name.
Anne of Denmark had placed in his custody portraits of Albert VII, Archduke of Austria and Isabella Clara Eugenia.
[44] The French ambassador Antoine Lefèvre de la Boderie regarded Fowler as a useful source of information, worthy of cultivation, describing him as an "Ecossais et un galant homme, que je desir bien entretenir".
His will mentions a chain of gold of jewels worth £300, and three diamond rings, presents from Anne of Denmark, which he left to his brother John Fowler.
[59] The verse on the tree was:Perpetuo vernans arbor regnantium in Anna,Fert fructum et frondes, germine laeta vivo.
[64] The figurative image of Anne of Denmark as a fruitful vine, an olive tree with four branches, was used in a speech in parliament made after the Gunpowder Plot by Thomas Egerton, 1st Viscount Brackley as Lord Chancellor.
[65] His nephew William Drummond of Hawthornden bequeathed a manuscript collection of seventy-two sonnets, entitled The Tarantula of Love, and a translation (1587) from the Italian of the Triumphs of Petrarke to the library of the University of Edinburgh.