Doctor Who’s Ncuti Gatwa addresses surprise exit after just two series

"It's a role that demands a lot of you, physically and emotionally and mentally."

In Saturday, May 31's episode of the classic time-travel show (titled 'The Reality War'), Gatwa's Doctor sacrificed himself to save baby Poppy, leading to a regeneration nobody saw coming.

That regeneration proved even more monumental than usual, as it was Billie Piper's character Rose Tyler he morphed into.

In a behind-the-scenes Doctor Who featurette, Gatwa was candid when addressing his surprise departure.

"It's a role that demands a lot of you physically and emotionally and mentally," he began.

"The actors playing the Doctor are only actors playing the Doctor. Unfortunately, we are mere mortals. I would love to have the energy and the youth to be able to do this full time for the rest of my life, but my knees are telling me it's time."

The Sex Education and Barbie actor lodged a more gooey message when his final scenes aired on BBC One.

"You know when you get cast, at some point, you are going to have to hand back that sonic screwdriver and it is all going to come to an end, but nothing quite prepares you for it," said Gatwa.

"This journey has been one that I will never forget and a role that will be part of me forever. There are no words to describe what it feels like to be cast as the Doctor, nor are there words to explain what it feels like to be accepted into this iconic role that has existed for over 60 years and is truly loved by so many across the globe.

"The fans are truly the final character and beating heart of this show and I can't thank the Whoniverse, and the Whovians, enough for welcoming me in, and making this such a touching experience. I've loved every minute of it, but now is the time to hand over the keys to that beloved blue box and let someone else take control and enjoy it every bit as much as I have. I'll truly miss it, and forever be grateful to it, and everyone that has played a part in my journey as the Doctor."

This comes after reports emerged last month suggesting Gatwa was set to get the chop after a poor return in viewing figures.

An insider also told The Sun that the star was ready to leave in a bid to expand his Hollywood filmography.