Simply titled The Last One, millions tuned in as the episode brought the hit comedy to a close 20 years ago, on 6 May 2004, finally resolving the decade-long "will they, won't they?" romance between Ross and Rachel.

It was the end of an era for its stars - Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc, Matthew Perry and David Schwimmer - and fans around the world.

Looking back at the final shows in an interview with NBC's Today show in the US, Friends creators Marta Kauffman and David Crane revealed details of the leak.

"Oh my god, we tried so hard to keep it a secret!" Kauffman said. "We were desperate to keep it a secret and it got out. And it was an inside job."

Scripts sent out ahead of the premiere of the final episode were numbered, Crane explained.

"We knew how many people knew what it was going to be," he said. "So it did, through an element of... it became a behind-the-scenes detective show.

"It was frustrating, but at the end of the day, what are you gonna do?"

Part of the script that leaked included the details of Ross and Rachel finally getting back together, Kauffman said.

But when asked if the mystery of who released the information was solved, she replied with a smile: "Ish."

"Ish," Crane repeated.

After 10 series and 236 episodes, as well as Ross and Rachel's reunion, the final instalment saw Monica and Chandler leaving their famous Manhattan apartment and moving to the suburbs as new parents to adopted twins.

Perry, who died last year, aged 54, wrote about the finale in his 2022 memoir, Friends, Lovers, And The Big Terrible Thing.

Read more from Sky News:
Matthew Perry obituary: The one who made everyone laugh
The Friends reunion: The one where they got back together

"Before that final episode, I'd taken Marta Kauffman to one side," he wrote. "'Nobody else will care about this except me', I said. 'So may I please have the last line?'"

His character Chandler did indeed have the last line. As the Friends decide to go for one last coffee before the move, he simply asks, "Where?", in a trademark sarcastic but poignant joke about the fact that so much of their time on screen has been spent in the Central Perk coffee shop.

"It's incredibly poignant. It's a legacy for him, one of his many legacies," Kauffman said.

Friends has found a new generation of fans in recent years after being picked up by streaming sites.

Earlier this year, two scripts for The One With Ross's Wedding, season four's famous two-part finale filmed in London, sold at auction for £22,000 after being found in a bin.