This story certainly has a long pedigree, and even if, as is typical with such fundamentally private matters, there is uncertainty as to what actually occurred, it is generally accepted that Byron did have sexual experiences of some sort from the age of nine, and such detail as survives appears to have originated ultimately with the poet himself.

Byron's most recent major biographer, Fiona McCarthy, sets out the details as follows: the incidents began when the future poet was living in Aberdeen with his mother, in significantly reduced circumstances caused by his father's profligacy and early death. They involved a local "free girl" named May Gray, who had been hired by the mother as a servant and nurse, and who "used to come to bed with him and play tricks with his person". When this was discovered, and the boy admitted the encounters, she was "sent off". This, McCarthy adds, "was presumably the episode to which Byron was referring when he wrote in his journal, "My passions were developed very early – so early – that few would believe me – if I were to state the period and the facts which accompanied it." (Cochran, in his study of Byron's sexuality, disputes the two passages are connected.)

Gray's "tricks" (we have no further details of exactly what they comprised) seems to have continued for two or three years, in the period c.1798-1799. We know nothing more of what occurred, or with what frequency, though it would seem likely that the encounters became more common later on, when Byron and Gray were living in lodgings together in Nottinghamshire, than they would have been in the cramped apartment the future poet shared with his mother in Aberdeen. Certainly it does seem true that once the superficially pious and respectable Gray was away from the watchful eyes of other members of the family, she quickly began to attract disapproval in local high society. Ann Parkyns, a friend of the Byron family, noted that she was often drunk, and the Byrons' socially ambitious solicitor, John Hanson, was sent to interview the boy, writing to Byron's mother that:

He told me that she was perpetually beating him, and that his bones sometimes ached from it; that she brought him all sorts of Company of the very lowest Description into his apartments; that she was out late at nights, and he was frequently left to put himself to bed... But Madam this is not all; she has even traduced yourself.

Nothing in the surviving Byron correspondence, however, explicitly relates to sex, and the details of Gray's sexual encounters with Byron emerged only much later – the first edition of the Oxford Dictionary of National Biography (1886) very conventionally claimed that the poet was and remained "passionately fond" of his nurse, and it was only starting in the 1950s that Byron's biographers have felt able to discuss the reality of what occurred.

In this context, it needs to be observed that the information that we have is really only at third hand, though the apparent respectability of the parties concerned has led Byronists to accept the details as accurate. Still, it's worth noting that, to trust the account, we have to place credence not only in what Hobson the lawyer claimed that the 11 or 12-year-old Byron told him, but also in what one of Byron's closest friends, the radical Whig politician and diarist John Cam Hobhouse, 1st Baron Broughton (1786-1869), claimed that Hobson told him after Byron's early death in 1824. Hobhouse's papers and diaries – which passed to the British Museum and subsequently to the British Library as the Broughton Papers, with the stipulation that they not be opened until 1900 – are the actual source of the few details that we now have.

Anyway, I think it's well worth concluding by pointing out that we need to see the incidents not, as Rotten.com and other online resources have generally tended to, as ones that resulted in Byron "losing his virginity" and discovering the pleasures of sex at an uncommonly early age. After meeting with Hobson and telling the layer what had transpired, the young Byron followed up with a letter begging that the nurse be dismissed and sent away, rather pathetically signing it from "your young friend" – so the evidence we have portrays not an adolescent who was uncommonly adventurous and mature for his age, but rather a boy traumatised by a serious case of child abuse.

McCarthy summarises the situation as follows:

The May Gray episode had important repercussions. Byron's nurse was ostentatiously religious, and the coexistence of pious Bible study and lascivious behaviour sharpened his awareness of hypocrisy and cant, deepening his scorn of false religiosity and over-zealous Calvinism in particular. The strange and furtive memories of sex being forced upon him at this early age also influenced Byron's sexual development, to the point where he negated the physicality of sex even as he indulged it. There are echoes of May Gray in a journal entry for December 1813: "A true voluptuary will never abandon his mind to the grossness of reality. It is by exalting the earthly, the material, the physique of our pleasures, by veiling these ideas, by forgetting them altogether, or, at least, by veiling these ideas, by forgetting them altogether, or, at least, never naming them hardly to one's self, that we alone can prevent them from disgusting."...

The memories of female dominance, the large nurse in the small bed, affected his later attitudes to sex with women. Byron found a mature woman a complicated structure, threateningly flabby. He preferred the physique of young teenage boys, or the girls dressed as boys that became a feature of his early days in London. Byron's preferred bodies would be youthful, lithe and firm.

We don't know much, finally about May Gray's background. She was Scottish, apparently aged around 30 at the time of the incidents, and came from the Aberdeen area; after leaving the Byrons' service, she "returned to her native country," married respectably, and died around 1843.

Sources

George Gordon Byron, The Complete Works of Lord Byron (1846)

Peter Cochran (ed.), Byron and Women (and Men) (2010)

Kasimir Edschmid, The Passionate Rebel: the Life of Lord Byron (1930)

Fiona McCarthy, Byron: Life and Legend (2014)