How to make the perfect Christmas TV special

• What is on TV this Christmas?
• Everything you need to know about the Call the Midwife Christmas Day special
• What time is the Strictly Christmas special on TV?

Even the legends have struggled to deliver the perfect TV Christmas.

"They definitely felt the pressure," Barry Cryer, comedian and one-time writer for Morecambe and Wise, says of the comedy double act during their Christmas heyday. "With the Christmas specials, they always felt pressure to top the last one. It meant that they were very satisfying to work with – but weren’t easy to write for."

The era of huge comedy specials is over. No Morecambe and Wise, no Two Ronnies. Instead big British dramas dominate – Call the Midwife, Doctor Who, Victoria – joined by the festive edition of Strictly Come Dancing and the obscenely popular Mrs Brown's Boys.

How easy is it for these major shows to create something specifically for Christmas? And do they ever feel the pressure of living up to the ghosts of Christmas TV past?

We spoke to three different people from three very different shows who have first hand experience of making a Christmas special: Call the Midwife exec producer Pippa Harris, Strictly Come Dancing producer Charlotte Brookes, and Ruth Jones, star and co-creator of Gavin & Stacey, one of the biggest Christmas comedy specials of recent years and now available to watch again for free on BBC iPlayer.

Here's how they do it.

'We always end up filming Christmas in summer'

Snow. It's the one ingredient that almost every Christmas TV special calls for, no matter how artificial the effect or unlikely the weather. Just like advent calendars and adverts, television is designed to feed our White Christmas fantasies.

At least the snow in 2017's Call the Midwife Christmas special is historically accurate.The BBC drama this year is set during the bitter winter of 1962/3, when Arctic conditions brought the country to a standstill. Perfect for a frosty festive backdrop, but less helpful when the episode has to be filmed in the height of summer.

"The irony is we always end up shooting the Christmas special either in late spring or early summer," Call the Midwife producer Pippa Harris explains. "It’s normally pretty hot, but with this episode in particular, because it was meant to be very cold, everyone was wrapped up the whole time in scarves, hats, gloves and coats. The poor actors were often sweltering in the heat of their costumes.

"The art department spent days setting up these fake snowdrifts and putting frost on the windows. Everything looks like a winter’s day, but in actual fact it was filmed in May."

Ruth Jones too remembers struggling to get into the Christmas spirit when she and co-creator James Corden first sat down to write the Gavin & Stacey 2008 special the summer before.

"Writing it was really weird: we were in a really hot hotel in the West End in the middle of summer," Jones says. "We tried to save money by not ordering room service, and tried to make boiled eggs by putting two raw eggs in the insulated ice bucket and filling it with boiling water hoping they would cook. They didn’t and they were disgusting. Christmas seemed a very long way away."

By the time the Gavin & Stacey cast gathered to film the series however, it was beginning to look a lot more like Christmas– complete with seasonal illnesses.

"We filmed it in October and I remember everyone got struck down with flu so we had to have an on-set doctor," Jones says – and it's true, you can definitely hear how bunged up some of the cast are in the finished episode.

"But for the most part it was really good fun. The Christmas dinner was actually a proper dinner cooked in Pam’s pretend kitchen! And it was lush."

For the Strictly Come Dancing Christmas special meanwhile, the trick to creating a festive atmosphere is to make the show feel live even when it isn't.

Unlike the regular series, this is pre-recorded – even Bruno Tonioli isn't going to bound out of bed on Christmas morning and head to the studio.

The entire production team wears Christmas jumpers, there’s a roast dinner in the canteen – it’s full on Christmas in the Strictly studio

"I start working on it in the beginning of October, which is quite early to start listening to Christmas songs!" producer Charlotte Brookes says.

The competition itself is filmed in one go at the very end of November: "When we film it really feels like Christmas Day in the studio," Brookes says. "The entire production team wears Christmas jumpers, there’s a roast dinner in the canteen – it’s full on Christmas in the Strictly studio."

The whole thing is designed to make the celebrities – and the audience – feel as Christmassy as possible.

"It takes a day to get the studio ‘Christmas ready’," Brookes explains. "We have two truck-loads of decorations and two 18ft trees at the back which need cherry pickers to decorate. I think we used something like 3000 baubles to decorate the studio. We use rich warm colours to make it feel super festive. It looks beautiful."

'Call the Midwife fundamentally likes telling stories about the good in people'

Call the Midwife writer Heidi Thomas is the undisputed Queen of Christmas TV in 2017. Last year's Midwife was the most watched show of the festive period, and this year, as well as the Midwife special, she has also written the three-part BBC adaptation of Little Women which will air from Boxing Day.

It's an impressive achievement, particularly given the fact that her storylines aren't always on the face of it particularly full of Christmas cheer. Painful pregnancies and family tragedy drive many of the plots of Midwife, while any reader of Little Women will know to have tissues at the ready when they tune in to see the adaptation on screen...

"We never shy away from tough subject matter," Midwife producer Harris says. "But what writer Heidi Thomas is so brilliant at is the way she combines that with joy and, ultimately, an uplifting take on whatever it is she’s exploring, be that an abandoned baby or an unexpected pregnancy."

She adds, "Her style of writing – being able to combine dark and sorrowful subject matter with humour and wit and lightness – is quite a rare combination.

"Also she fundamentally likes telling stories about the good in people: the community spirit, people pulling together, the idea of Poplar as a microcosm for the whole country. By and large people do put themselves out for others. They are kind.

"Heidi reminds everyone of those values, and they sit very well at the heart of Christmas. That sense of community, doing something for others, giving gifts – that is all quintessentially Heidi Thomas and quintessentially Christmas."

For Ruth Jones and James Corden meanwhile, the aim when writing the Gavin & Stacey Christmas special was to get out in the open everything that made them laugh about awkward Christmas family get togethers.

"The Christmas card issue was a particular annoyance," she says. "Like, you know, everyone gets cards every year written ‘from John’. Who’s JOHN? Which John? I know four Johns! What’s the point of even spending money on the stamp just to say ‘from John’?

"And also the stress around the turkey prep: whose instructions do we follow? Jamie’s? Nigella’s? Delia’s? Then there’s always the really awful present, like 'talc'. What actually IS talc? One of my favourite moments is when Nessa and Dave give everyone a solitary Celebration chocolate. And Gwen gets the Bounty. No comment."

Christmas Day is a rare occasion in which the whole family watches TV together

Strictly producer Charlotte Brookes explains that while the regular series will grip people for weeks on end, the one-off Christmas special allows them to bring something new.

"Each year we do a short film with different groups in the community to raise awareness about a particular subject," she says. "Last year we threw a Strictly party with a mental health charity, the year before that we worked with young carers.

"This year we wanted to talk about active ageing, and the importance of staying fit as you get older," she says. "So we invited lots of tea dance communities who reap the benefits of dancing – both socially and health-wise – to Buckingham Palace. The Duchess of Cornwall is the President of the National Osteoporosis Society, so she is also very interested in encouraging people to stay fit and active as they get older."

The Christmas special aims to do what Strictly does best: bring the generations together.

"Christmas Day is a fairly rare occasion in which the whole family watches TV together," Brookes says. "More often than not we have the young right through to the very old, and my aim is to have something that appeals to everyone."

It makes me feel proud, silly, sad, happy, old and very very Christmassy

After working for months on end on their Christmas specials, it's tempting to assume that the last thing any of these people would want to do would be to turn on the telly again come Christmas Day itself.

Apparently not.

"After working on last year’s special I still watched it!" Strictly's Brookes says. "I like watching it go out; it’s nice watching it with other people, because you see it with fresh eyes."

Call the Midwife producer Harris says that while she may not tune in 'live', she will still watch the episode at Christmas, adding that the option of catching up on demand afterwards may explain why big dramas have replaced the likes of Morecambe and Wise.

"Morecambe and Wise for me as a kid was real appointment to view, but I don’t know whether there’s an equivalent now. My family is biased so we do all sit down to watch Call the Midwife," she says.

"Drama is going through a golden period, and there are a number of big shows that audiences love to see at Christmas," she adds. "What has perhaps played in drama’s favour is how easy it is to catch up nowadays. iPlayer means you can watch whenever you want, and dramas fare particularly well in that situation. Whereas perhaps comedy and entertainment shows are more geared to being watched ‘in the moment’."

Gavin & Stacey's Christmas special episode aired almost a decade ago, so for Jones watching the episode back comes with its own nostalgia.

"I’ve seen it a couple of times," she says. "It makes me feel proud, silly, sad, happy, old and very very Christmassy. Such happy times writing it, and a joy to film because by then we were a big happy family and it was like we were all getting together for Christmas.

"On a personal level I love the Santa’s grotto scenes because my nephew Zakk played the little boy sat on Nessa’s lap. Zakk is now 18 and drives a car, but he was this cute little kid back then!"

Making TV for Christmas can be anxiety-inducing, difficult, and often distinctly unfestive. And yet, all that work provides the fictional families that millions of us, year on year, choose to spend Christmas with.

These are the people who make our Christmas dreams come true – even if we do still kid ourselves it was better when we were younger.