|Occupation||Deputy-chamberlain and antiquary|
On the authority of Anthony à Wood it has been stated that he was appointed by Sir Nicholas Throckmorton to be deputy-chamberlain in 1570, and that he held this office for forty-five years. His patent of appointment, however, preserved in the Rolls Office, proves that he succeeded one Thomas Reve in the post on 11 July 1603. With his friends, Sir Robert Cotton and William Camden, he was one of the original members of the Society of Antiquaries.
- Opinion touching the Antiquity, Power, Order, State, Manner, Persons and Proceedings of the High-court of Parliament in England
- Of What Antiquity Shires were in England?
- On the dimensions of the lands of England
- The Authority, Office, and Privileges of Heralds in England
- Of the Antiquity and Privileges of the Houses or Inns of Court, and of Chancery
- Of the diversity of names of this island
He also wrote a large work on the Domesday Book titled Tractatus de usu et obscurioribus verbis libri de Doomsday (lit. A Treatise on the Use and Meaning of the obscure Words in the Doomsday Book) as well as a guide book for his successors in office containing a catalogue of the records of the Treasury and an account of treaties with foreign nations.
Agarde died on 22 August 1615 and was buried in the cloister of Westminster Abbey, on his tomb being inscribed Recordorum regiorum hic prope depositorum diligens scrutator. He bequeathed to the exchequer all his papers relating to that court, and to his friend Sir Robert Cotton his other manuscripts, amounting to twenty volumes, most of which are now in the British Museum.
- Society of gentlemen (1780). The Biographical Dictionary, Or, Complete Historical Library: Containing the Lives of the Most Celebrated Personages of Great Britain and Ireland, Whether Admirals, Generals, Poets, Statesmen, Philosophers, Or Divines : a Work Replete with Instruction and Entertainment. F. Newbery. p. 23.
- Chisholm 1911.
- Sir Nicholas' left separate legacies in his will dated 8 February 1570 to Margaret Butler and Arthur Agard
- M. Hoefer, Nouvelle Biographie Générale. Paris, France: Firmin Didot Frères, Fils et Cie, 1857. Agard was friendly with Robert Cotton with whom he corresponded by testament, all of the manuscripts which were not mentioned in the catalog on display at the Cottonienne [Cottonian] library now found at Oxford. It has been on exhibition at Westminster Abbey and a small monument has been erected to its memory along with an inscription, mostly unreadable/erased from which we can read the name of his wife Marguerite, daughter of George Butler of Sharnbrook.