The “special mini adventure” will form two four-minute episodes, titled ‘Space’ and ‘Time’, starring Matt Smith alongside regular cast members Karen Gillan and Arthur Darvill.

Brand manager Edward Russell told the latest issue of Doctor Who Magazine: “While [1999 Comic Relief special] ‘The Curse Of The Fatal Death’ was a Doctor Who parody, this is a full on, 100% legitimate mini-story…”

He continued: “It’s written by Steven Moffat and directed by Richard Senior, who also directed the recent National Television Awards scene. It’s set entirely inside the TARDIS… and outside the TARDIS. At the same time. In fact, over several times! Yes, it’s one of Steven’s crazy, timey-wimey plots and i can guarantee some laugh out loud moments.”

Russell commented: “The adventure is split into two halves, so fans can expect a proper cliffhanger at the end of Part One. I don’t want to give away any more than that, but fans of Amy’s legs will not be disappointed.”

It was reported last month that the episodes will feature two Amy Ponds.

Russell also confirmed that the mini-adventure has its own title sequence and on-screen title.

Red Nose Day 2011 takes place on Friday 18th March. The charity helps to transform the lives of poor, vulnerable and disadvantaged people across the UK and Africa.

Issue 432 of Doctor Who Magazine is available in shops now.