After his release the couple lived in straitened financial circumstances until, with the accession of Elizabeth I in late 1558, Dudley became Master of the Horse, an important court office.

It was rumoured that the Queen soon fell in love with him and there was talk that Amy Dudley, who did not follow her husband to court, was suffering from an illness, and that Elizabeth would perhaps marry her favourite should his wife die.

In the morning of 8 September 1560, at Cumnor Place near Oxford, she insisted on sending away her servants, and later was found dead at the foot of a flight of stairs with a broken neck and two wounds on her head.

[8] The Earl of Warwick and future Duke of Northumberland was the most powerful man in England, leading the government of the young King Edward VI.

[23] By late 1559, several foreign princes were vying for the Queen's hand; indignant at Elizabeth's little serious interest in their candidate,[24] the Spanish ambassador de Quadra and his Imperial colleague were informing each other and their superiors that Lord Robert was sending his wife poison and that Elizabeth was only fooling them, "keeping Lord Robert's enemies and the country engaged with words until this wicked deed of killing his wife is consummated".

[32] The house, an altered 14th century monastic complex, was rented by a friend of the Dudleys and possible relative of Amy, Sir Anthony Forster.

[38] A portrait miniature of the same woman was sold at Sotheby's in 1983 by the Duke of Beaufort, a direct descendant of Lettice Knollys, who was the second wife of Amy's widower Robert Dudley.

[41][42] On Sunday, 8 September 1560, the day of a fair at Abingdon, Amy Robsart was found dead at the foot of a set of stairs at Cumnor Place.

Robert Dudley, at Windsor Castle with the Queen, was told of her death by a messenger on 9 September and immediately wrote to his steward Thomas Blount, who had himself just departed for Cumnor.

[46] A few days later Blount wrote that some of the jury were no friends of Anthony Forster (a good sign that they would not "conceal any fault, if any be") and that they were proceeding very thoroughly:[47] they be very secret, and yet do I hear a whispering that they can find no presumptions of evil.

[49] Dudley, desperately seeking to avert damage from what he called "my case",[50] was relieved to hear the impending outcome, but thought "another substantial company of honest men" should undertake a further investigation "for more knowledge of truth".

[47] The coroner's verdict, pronounced at the local Assizes on 1 August 1561,[51] was that Lady Amy Dudley, "being alone in a certain chamber … accidentally fell precipitously down" the adjoining stairs "to the very bottom of the same".

She was buried at St. Mary's, Oxford, on 22 September 1560 with full pomp,[54][55][56] including attendance by the Garter King of Arms and other heralds,[57] which cost Dudley some £2,000 (roughly £1 million in 2021).

[58] He wore mourning for about six months but, as was within custom, did not attend the funeral, at which Lady Amy Dudley's half-brothers and neighbours, as well as prominent city and county citizens, played leading parts.

[60] Amy Dudley's death, happening amid renewed rumours about the Queen and her favourite, caused "grievous and dangerous suspicion, and muttering" in the country.

[62] William Cecil, the Queen's Principal Secretary, felt himself threatened by the prospect of Dudley's becoming king consort and spread rumours against the eventuality.

[64] Likewise strongly opposed to a Dudley marriage, Nicholas Throckmorton, the English ambassador in France, went out of his way to draw attention to the scandalous gossip he heard at the French court.

[58] Elizabeth's affection and favour towards him was undiminished,[58] and, importuned by unsolicited advice against a marriage with Lord Robert, she declared the inquest had shown "the matter … to be contrary to which was reported" and to "neither touch his honesty nor her honour.

[69] Dudley himself had no illusions about his destroyed reputation, even when he was first notified of the jury's decision:[49] "God's will be done; and I wish he had made me the poorest that creepeth on the ground, so this mischance had not happened to me.

"[70] In September 1561, a month after the coroner's verdict was officially passed, the Earl of Arundel, one of Dudley's principal enemies, studied the testimonies in the hope of finding incriminating evidence against his rival.

[74] Appleyard, instead of giving answers, retracted all his statements; he had also requested to see the coroner's report and, after studying it in his cell, wrote that it fully satisfied him and had dispelled his concerns.

[83] The notion that Amy Robsart was murdered gained new strength with the discovery of the Spanish diplomatic correspondence (and with it of poison rumours) by the Victorian historian James Anthony Froude.

[13] Generally convinced of Leicester's wretchedness,[84] he concluded in 1863: "she was murdered by persons who hoped to profit by his elevation to the throne; and Dudley himself … used private means … to prevent the search from being pressed inconveniently far.

[86] Much more scholarly and influential was an 1870 work by George Adlard, Amy Robsart and the Earl of Leycester, which printed relevant letters and covertly suggested suicide as an explanation.

Pollard was convinced that the fact that Amy Robsart's death caused suspicion was "as natural as it was incredible … But a meaner intelligence than Elizabeth's or even Dudley's would have perceived that murder would make the[ir] marriage impossible.

[89] In the absence of the forensic findings of 1560, it was often assumed that a simple accident could not be the explanation[90]—on the basis of near-contemporary tales that Amy Dudley was found at the bottom of a short flight of stairs with a broken neck, her headdress still standing undisturbed "upon her head",[91] a detail that first appeared as a satirical remark in Leicester's Commonwealth and has ever since been repeated for a fact.

As further arguments for suicide have been forwarded the fact that she insisted on sending her servants away and that her maid Picto, Thomas Blount, and perhaps Robert Dudley himself alluded to the possibility.

[93] Apart from alternatives for a murder plot as causes for Amy Robsart's death, his correspondence with Thomas Blount and William Cecil in the days following has been cited as proofs of his innocence; the letters, which show signs of an agitated mind, making clear his bewilderment and unpreparedness.

Professor Ian Aird wrote: "The exact site of Amy’s grave has never been known, though in the contemporary account it was said to have been at the east end of the church of St. Mary the Virgin in Oxford.

A memorial tile in the church, however, pays tribute to her:In a Vault of brick at the upper end of this Quire was buried Amy Robsart Wife of Lord Robert Dudley K.G.