Number four, Privet Drive might be the most relentlessly non-magical environment in the Harry Potter books but the wiper of its pristine surfaces had a surprising secret.

Aunt Petunia vowed, along with her husband Vernon, to ‘stamp out’ her nephew’s magic. But, thanks to the memories of Severus Snape, we know that Petunia once held different aspirations.

Magical sibling rivalry

The bony and horse-faced aunt we met in Philosopher’s Stone seemed almost like a cartoon caricature: a woman cruel enough to deny her orphaned nephew a proper place in her family, mean enough to underfeed him and even make him sleep in a cupboard. But she wasn’t always this way.

Before she became the Marigolds-wearing Mrs Dursley we know and loathe, Petunia Evans – or ‘Tuney’ as her sister called her – actually longed to be a witch.

It wasn’t until that ‘awful boy’ – the Evans family’s young neighbour Severus Snape – noticed Lily’s burgeoning magic (she was practically flying off a garden swing at the time) that Petunia realised what her sister really was.

‘Remember my last’

Petunia’s disdain for Harry was most likely born from a long-standing jealousy of her magical sister, Lily. A Howler from Dumbledore, addressed to Petunia, said ‘Remember my last’ – no doubt referring to the letter which he left with baby Harry, on the doorstep of Privet Drive. But there was another occasion when Albus had a reason to write, and it had long-lasting consequences.

The Hogwarts headmaster sent a kindly response to Petunia when she wrote to him as a child, begging to join Hogwarts. After Dumbledore’s gentle rejection, ‘Tuney’ started referring to her sister as a ‘freak.’

Disappointed and bitter, Petunia spied on Lily and Snape as they became fast friends, and she picked up morsels from the wizarding world she could never join.

When Petunia blurted out a competent description of a Dementor, Harry was more surprised than Uncle Vernon to hear her speak of ‘Azkaban’. Even Petunia, so intent on hating the magic she never had, was appalled when she learned of Voldemort’s return – it was the one moment when Harry realised she truly was her mother’s sister.

She might have provided Harry with a childhood home but it was clear that her thwarted magical ambitions likely turned Petunia into the person she became – one who cared more for the surgical cleanliness of her worktops than the wellbeing of her sister’s son.

During her final parting with Harry, she stopped for a moment, as if to say something. She never did, of course, but that faltering second said a lot about her as a character.

A Hogwarts life that never was

If Petunia had been a witch, would she have been a nicer person, devoid of bitterness? Or would she have fallen in with the wrong crowd?

Maybe, unlike Lily, she would’ve teamed up with Draco Malfoy's mother, Narcissa, or even Dolores Umbridge. They could’ve bonded over their mutual interests in garish tea sets. Alas, we will never know.

Petunia may have said and done a lot of bad things in her life, but it was a life arguably born out of sadness. A life of living in her sister’s magical shadow. As such, those glimmering moments where Petunia revealed her connection to the magical world were intensely fascinating.

The look on her face when she met Professor Dumbledore as an adult was priceless. After all, this was the man she once wrote to, wanting so badly to go to Hogwarts. Her final moment with Harry – so nearly speaking, but falling silent – speaks many volumes we will never hear.