Severus Snape intimidated Hogwarts students and Harry Potter fans for years - but Alan Rickman was a world away from his character.

In an old video of the actor rediscovered after his tragic death last week, it's revealed the star - who tragically died last week following a battle with cancer - once used a fart machine to prank a young Daniel Radcliffe.

Behind the scenes footage from the Prisoner of Azkaban, which was released in 2004, shows the students lay in sleeping bags as Rickman and Sir Michael Gambon - in character as Snape and headmaster Albus Dumbledore - walk amongst them.

(Image: ShenronAlt/Youtube) (Image: ShenronAlt/Youtube)

In the video, rude noises are heard coming from Daniel's sleeping bag, just as Gambon says: "In our dreams, we enter completely our own world, you know, it's completely our own world."

Read more:Alan Rickman and Harry Potter fans leave tributes to actor in fitting location

As the interruptions continue, Rickman - who was also in on the joke, along with director Alfonso Cuaron - can be seen struggling to hold back his laughter.

(Image: ShenronAlt/Youtube) (Image: ShenronAlt/Youtube)

Cuaron explained: "It was very good, because there was a bunch of sleeping bags, and Dan [asks] us to have his sleeping bag next to this particular girl he fancied."

Daniel, speaking with castmates Emma Watson and Rupert Grint at the time, recalled: "We've just done a take, finished the take, and they're taking ages to get it...

"They had put a fart machine into my sleeping bag, and Michael Gambon had actually been pressing it during the take, I found out."

(Image: ShenronAlt/Youtube)

Meanwhile, J.K. Rowling has revealed that she told Rickman the secret of the Harry Potter story - that his character was in love with Harry's mother Lily - before she'd even finished the books.

A fan asked whether Rowling would ever share the secret she had told Rickman, Rowling responded: “I told Alan what lies behind the word ‘always’.”

In the seventh and final book from the series, Harry Potter And The Deathly Hallows, Snape’s secret love for his childhood friend Lily was revealed.

Professor Dumbledore then asks Snape if he had been in love with Lily the whole time, and he replied with just the one word, “always”.

“She [Rowling] gave me one tiny, little, left of field piece of information that helped me think that he was more complicated and that the story was not going to be as straight down the line as everybody thought,” he said in a 2011 interview.