The cast of Peter Jackson's Lord of the Rings films reunited for a one-off YouTube event.

During the special (titled "One Zoom to Rule Them All") which was held as part of Josh Gad's Reunited Apart series, actors including Sir Ian McKellen, Elijah Wood, Orlando Bloom and Sean Bean exchanged anecdotes and behind-the-scenes secrets from the hit fantasy epics.

Jackson spoke about a scene in which Boromir (Bean) says the line, "one does not simply walk into Mordor", which subsequently became a popular Internet meme.

"That entire speech that Sean had to deliver at the Council of Elrond was written the night before," the director explained. "It's long and we gave it to Sean the morning he arrived. What Sean did, which I thought was really clever, is he got a print-out of the speech taped to his knee."

"If you watch the scene now, you'll see every time that Sean has to check his script."

McKellen also revealed that he filmed one of his best-known scenes (in which he says: "a wizard is never late") on his very first day of filming.

The veteran actor then filmed the final scene in the final movie just two days later. "I had to meet the Hobbits and say goodbye to them - I'd never met them before!" he joked.

Jackson also reminisced about the proposed adaptation of JRR Tolkein's novels starring The Beatles, which almost came to fruition in the 1960s.

The full video can be watched here, and features many more stories from behind the scenes of Lord of the Rings.