Meet Nate, the baby with Down's syndrome who plays newborn Robert in Call the Midwife

The show was, indeed, Call the Midwife (of which Charlotte is an "absolute super-fan") – and three weeks later, Nate had his chance to shine. In the season 10 finale, little Nate plays a baby called Robert who is diagnosed with Down's syndrome shortly after his birth; and so he was made up like a newborn again, with oils and fake blood for the childbirth scene, and cute 1960s outfits for the rest.

Call the Midwife's Down's syndrome storyline

At the start of episode seven, heavily-pregnant Blanche Dellow (Madeleine Worrall) is cheerfully ready for her younger sister Sylvia (Charlotte Hamblin) to adopt her baby after its birth. She is an older mother, with three daughters already, and she knows that Sylvia is desperate for a child after struggling with infertility. But (spoiler alert) when the baby is born, the nurses and Dr Turner (Stephen McGann) realise he has Down's syndrome.

Sylvia is devastated, and rejects the son she had already named "Justin"; but Blanche falls in love with him, and re-names him "Robert". She and her husband Walter (Michael Begley) decide to raise Robert themselves, though Walter requires a bit of emotional support from Fred Buckle (Cliff Parisi) and some time hanging out with Reggie (Daniel Laurie) to help him understand that he can do this.

"We wanted to make sure that whatever storyline Nate was involved in, that we as a family were involved in, was supportive, was a positive one," says Charlotte. And despite Sylvia's rejection, the episode ultimately turns out to be positive as the Dellows – with the support of the midwives and local community – welcome Robert as a new member of their family.

How Call the Midwife looks after a baby on set

Over the years, hundreds of newborn babies have passed through the set of Call the Midwife – and the show is a well-oiled machine when it comes to looking after its youngest actors.

"We were so looked after," says Charlotte. She and Matt both went along with Nate for a day of filming: "We were picked up from our home, transported down there, met on set, breakfast provided immediately – 'Does Nate need any milk?' You know, it was bang on. He had his own little trailer. Not that we spent much time there, because he was on set – though he's only allowed on for a maximum number of hours.

"We were based in Nonnatus House, and he filmed in one room. Especially because of how cold it was, they wanted to make sure that he was looked after and that he was warm, so there was one centrally heated room and on all of his scenes were based in there. His changing room was Doctor Turner's office. It was lovely."

Nate, who is quite a laid-back baby, was "impeccably behaved" on set (says his father), although he showed off his smile a bit too much. "Every time somebody sort of waved at him, you give this immaculate smile, and they were like, 'No no, you've just been born, you're not meant to be this happy!'" recalls Charlotte.

The only time he got a little grumpy and tearful was when the team had to re-film the birth scene. "We had to strip him back off and soak him up with the oil and the fake blood and everything."

How does it feel for your baby to be in Call the Midwife?

You'd think it would be a slightly weird experience, standing on set to watch your baby 'being born' to its on-screen mother. But for Charlotte and Matt, it was a deeply emotional and "magical" experience to see Nate's birth recreated – this time so positively.

"I found it really magical because Nate had a post-natal diagnosis of Down's syndrome," says Matt. "And we were almost robbed of that opportunity. Because within seconds, he was taken away from us. For a heart murmur, and various, checks and things that have to be done for children with Down's syndrome.

"It was very different to our first – we've got a five-year-old boy, Zach. And it was a real magical moment when Zach was born, whereas when Nate was born it was so different. It was quite scary, and he was taken away from us. And on the set, it was quite magical, really, because that was our opportunity to almost –"

Charlotte adds: "He was in the spotlight, wasn't he? He was star of the room. Everybody was looking at him and praising him, for just being him. And that's what you should do when a baby's born. You should marvel."

Nate's on-screen debut also gives them a chance to show him off to the world – something they haven't really been able to do yet.

"Those first few weeks after he was born, because of COVID, we weren't allowed to invite people to hospital," says Charlotte. "And we were very shocked, and he was very poorly. He had lots of tubes and wires and plasters and all sorts. So we were reluctant to take photos because our five-year-old is very sensitive, so we didn't want to show him a poorly baby. But our plan all along, when we found out we were pregnant with our second, was Zach was to meet him first and then he would be introduced to the world.

"So for maybe about two weeks, we felt that we hid Nate. And we realise now it was probably a grief process. It was just a process of shock."

Now, she says, "We are proud, we are celebrating him, he is wonderful. And we can tell everybody. And what better way than putting him on TV!" The family have been sworn to secrecy until the episode hits our screens, and now they're delighted to surprise everyone they know.

Next up for Nate: a TV ad. "It amazes me that he's had these opportunities, like to have his face on TV at three months old is just mind blowing. And I can't wait to show him when he's older, like these little things that have happened," Matt says.

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Call the Midwife's representation of Down's syndrome

Nate's parents hope that viewers will come away from the episode knowing that worries and uncertainties are okay, but also with the assurance that having a baby with Down's syndrome can be a joy. Nate himself is now six months old, and despite his early health problems he is thriving. He's mastered the art of rolling; he's keen to sit up; he likes strawberries, but not broccoli.

Charlotte says: "Children are children and they'll learn at their own pace, at their own rate, in their own way. And you as parents and family, support them in whatever which way you have to. Because you want to, you love them. They are your family."

Matt adds: "If you were to take society out of the picture, and it's just you and your family, it wouldn't matter whether Nate had six arms. For me, like, I feel like a lot of the worries that you have as an individual or as a family, it's just judgement. And if you're just in your own bubble as a family, then why does it matter? If everyone's happy, then I think that's the biggest thing for me.

"I started to think long term, like: will Nate get bullied at school, will he ever get a job. They were my worries. But ultimately, if Nate's happy, I'm happy. And no matter where he's at, in life, if Nate has got a smile on his face, and he's happy, then I'm happy. And that's a big thing."

Charlotte is a big fan of Call the Midwife, and she is struck by how Reggie (Daniel Laurie), another character who has Down's syndrome, is written in the show.

"I think it's just: yeah, okay, Reggie is a character with Down's syndrome," she says. "But Reggie is a character on Call the Midwife. They don't address his Down's syndrome in every episode that he's in... He's just a character on set, and is treated equally. And I think that's lovely. It's wonderful. Like having different ethnicities, like having different religions – it's just representation, and it's lovely."

For more information about Down's syndrome, the Down's Syndrome Association has FAQs, a history of Down's syndrome, information for new parents, and a confidential helpline.

Call the Midwife seasons 1-10 are available on BBC iPlayer. Looking for something else to watch? Check out the rest of our Drama coverage or take a look at our TV guide.