Russell T. Davies has admitted casting Ncuti Gatwa in 'Doctor Who' was a "risk" because of his busy schedule.

Ncuti Gatwa's casting was a risk

Ncuti Gatwa's casting was a risk

The 31-year-old actor rose to fame as Eric Effiong in 'Sex Education' before stepping into the TARDIS and the showrunner admitted they were restricted by his prior filming commitments, but he still feels they got the right person as the 15th Timelord.

Russell told the latest issue of 'Doctor Who' magazine: “Casting Ncuti meant casting him before he’d finished on 'Sex Education'. That was a risk that we took, but it was absolutely the right risk, because it meant we got the best possible Doctor in 2024 that we could wish for."

And because of Ncuti's absence, Russell was able to push ahead with the idea he'd had for '73 Yards', in which Millie Gibson's Ruby Tuesday took centre stage.

He said: "I love a Doctor-lite episode. But, let’s face it, if Ncuti had been available, we would never have done a Doctor-lite episode in season 1...

"And the marvellous thing was, I’d had this idea kicking around for ages, of the Doctor and his companion stepping outside the TARDIS and seeing someone in the distance.

"But I could never make it work with two people. So when it became Doctor-lite – when it was just Ruby, and we were able to follow her whole life – it sort of freed itself.

“Also, I thought there was a nice balance, pairing it with 'Boom', which is such a character piece for the Doctor. That ended up dictating the shape of the series: a Doctor-heavy episode, followed by a Ruby-heavy episode."

Russell was delighted by Millie's "stunning" performance in the episode.

He added: “And I have to say, Millie is absolutely sensational. She walked in, from Coronation Street, onto leading this. No offence to Coronation Street, but that’s a big old runaway train, where you’re part of a cast of 70 or more. And suddenly, you’re in a cast of one, practically."