This climactic moment is redolent of the dramatic monologues of Robert Browning, one of the most celebrated poets of the Victorian age. Sensational pieces such as My Last Duchess (1842) and Porphyria's Lover (1836) centre on the doings of crazed protagonists who unwittingly reveal to the reader that they have murdered their beloved in order to be able to possess them completely and eternally. The parallels with the latter in particular, which is narrated by a murderer still locked in an embrace with Porphyria's corpse, are too strong to ignore.
Porphyria worshipp'd me; suprise
Made my heart swell, and still it grew
While I debated what to do.
That moment she was mine, mine, fair,
Perfectly pure and good: I found
A thing to do, and all her hair
In one long yellow string I wound
Three times her little throat around,
And strangled her.
Henry James was not only personally acquainted with Browning but also wrote extensively about his works and even delivered a public address on the centenary of his birthday, so it is unlikely that this echo is entirely accidental. Whilst preserving the governess's version of events, he uses the allusion to Porphyria's Lover to create a counter-narrative in which she is driven by delusion to commit an unspeakable act her conscious mind cannot allow and which she therefore projects onto an imagined other.
Julian Lopez-Morillas gives a suitably deranged rendition of Porphyria's Lover: