|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. He spent much labour in cataloguing the records and state papers, and made a special study of the Domesday Book, preparing an explanation of its more obscure terms. 
Thomas Hearne, in his Collection of Curious Discourses written by Eminent Antiquaries (Oxford, 1720), includes six by Agarde on such subjects as the origin of parliament, the antiquity of shires, the authority and privileges of heralds, etc. 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.
- 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.