Harry Potter fans just realising what Aunt Petunia is doing in kitchen scene

It has been almost 24 years since the first film in the Harry Potter franchise was released, and fans are loving them just as much now as they did then, with many patiently awaiting the upcoming TV adaptation.

The films were based on JK Rowling's book series of the same name, and follow 11-year-old orphan Harry Potter as he finds out he's a wizard and starts attending the magical Hogwarts School of Witchcraft and Wizardry, The film series features a swathe of famous British and Irish actors - including Fiona Shaw playing Harry's not-so-nice aunt Petunia Dursley, whom he lives with alongside his uncle Vernon and cousin Dudley, played by Richard Griffiths and Harry Melling respectively. Of course, Daniel Radcliffe plays the titular role.

While the Dursleys only make brief appearances in some of the films, they're a crucial part of the storyline as Harry has lived with them since the day his parents died when he was just one year old. But as with any book-to-film adaptation, it'd be impossible to include all the important details from the books that shows the true relationship between Harry and the Dursleys.

READ MORE: One of UK's 'prettiest towns' where 'everyone should go once in their life'

READ MORE: Oprah Winfrey responds to wild tsunami claim as thousands flee homes after earthquake

Today (July 31) is Harry Potter's birthday, according to the book and films - and fans discussing the franchise have only just spotted a detail in the first movie that only people who've read the book will understand.

In the beginning of the film - when Harry receives his first acceptance letter from Hogwarts - he carries the letter into the kitchen where Petunia can be seen standing in the background, wearing an apron as she stirs something in a large pot on the stove.

Taking to Reddit, one user pointed out this small detail and said that it shows something that's only every mentioned in the book.

"In Harry Potter and the Philosopher’s (Sorcerer’s) Stone, Aunt Petunia is visible in the background of this scene dyeing Dudley’s old clothes grey for Harry’s uniform. This is only ever mentioned in the book," the Reddit user wrote as the shared a photo from the film scene.

In the book, it is explained that all of Harry's clothes are hand-me-downs from his cousin Dudley. And as Harry is due to start a muggle school at the start of the new school year, Petunia dyes some of Dudley's old school uniform items.

Meanwhile, Dudley was preparing to start his new independent school, Smeltings Academy, which his father also attended. He is seen wearing the maroon uniform in the same scene as he sits at the kitchen table with Vernon.

Several people were amazed at learning this fact, as they took to the comments to share their bafflement that they hadn't noticed this before.

"i saw this as a kid and thought she was making soup out of leather," one person admitted.

"The amount of times I have seen this movie is crazy, and I’ve read the book once, absolutely loved it, and yet I didn’t even notice this. That’s actually really cool!! Just wish they kept Peeves in the film!" a second person wrote.

However, a third person said: "In a deleted scene/a different cut of the film Harry asks her about the clothes."

Another person asked why Petunia would do this, to which another person explained: "Because the Dursleys are pieces of shit to Harry and they’d rather send him to muggle high school with old dyed clothes instead of just buying him a uniform."