Stephen McGann pays touching tribute to BBC Call the Midwife's Cliff Parisi as he delves into off-screen bond

Set in 1971, the episodes split their storylines between Poplar and Hong Kong, as the residents of Nonnatus House are drawn into an emergency mercy mission following the collapse of the Order’s branch house in Kowloon.

Senior staff, including Sister Julienne and Dr Patrick Turner, travel to Hong Kong, where the Turners search for May’s biological mother and Sister Veronica faces an emotional encounter with an abandoned newborn.

Fred Buckle (Cliff Parisi) and Violet Buckle (Annabelle Apsion) are the first to arrive while visiting Violet’s son Derek, a police officer, but their trip takes a dramatic turn when they witness the aftermath of the collapse.

Back in Poplar, the younger midwives are left to manage Nonnatus House alone.

Storylines include Cyril’s interaction with a terminally ill neighbour during Hanukkah, Rosalind and Joyce hosting a festive gathering, and Sister Catherine supporting expectant mothers in an Irish Traveller camp.

Mr McGann, who plays Dr Turner, described filming overseas as a whirlwind and a striking change of pace from the show’s usual East End setting.

"It's a weird feeling going along in a rickshaw with a screaming director who can hardly be heard," he said."But it was great fun."

The actor also opened up about shooting in punishing heat and humidity, admitting the cast were taken aback by the conditions.

"Very hot indeed," he said. "When we got out there, it was like walking into a sauna. And all the locals were saying, ‘What are you filming here in summer for? We go inside. You're mad!'"

Mr McGann also highlighted filming aboard Hong Kong’s famous Star Ferry as a personal highlight of the trip.

"The Star Ferry is this old ferry that goes between Kowloon and Hong Kong Island," he said.

"We took one of them out into the big port area, which is one of the great vistas of the world. I was excited about that way before we started filming."

He added that the overseas storyline has a "very personal dimension" for the Turner family through their adopted daughter May’s connection to Hong Kong, and suggested the trip brought the cast together as a close-knit unit under pressure.

"We had so much to do in a relatively short space of time and we only had some of the cast, and we were like a cosy little team," he said.

"It was a gorgeous, frantic, hilarious, moving two weeks, which I hope will come across on screen."

Reflecting on his relationship with Mr Parisi, Mr McGann said he would "love, love, love" to have his co-star over for Christmas dinner, praising his humour and storytelling after years of working together on the long-running series.

"I would love, love, love to have Cliff over because he's just so funny and he tells such brilliant funny stories. He's a wonderful guy and a great mate," he said as he paid tribute.

Back in Poplar, the Christmas Special also promises classic festive warmth, with a parade, elaborate costumes, and party scenes for the younger midwives while some of the “grown-ups” are away.

Helen George, who plays Trixie Aylward, teased a typically emotional instalment, saying: "A Call the Midwife Christmas special would not be the same if one didn't shed a tear at some point."

However, she also promised "uplifting Christmas cheer", describing it as one of the most Christmassy specials yet.

Mr Parisi, meanwhile, revealed he has once again been tasked with playing Santa Claus, a role he has become closely associated with across the show’s festive episodes.

He did, however, joke that the experience hasn’t always gone to plan, recalling moments involving empty prop presents and confused children.