Posting on the official Instagram account for the series, the programme posted a number of images showing leading characters Rachel Shenton, Nicholas Ralph, Samuel West and more in character. However, many of the comments from fans were discussing how actor Callum Woodhouse was noticeably absent.
One person wrote: "Tristan's absence will be felt by me too! He's my favourite character. I hope he returns!" A second agreed, commenting: "Tristan/Callum is part of the magic, please do whatever it takes to bring him back."
A third added: "Not too excited honestly with the exit of Callum Woodhouse as Tristan. He was brilliant playing such an important and beloved Character in the books and series. Disappointed."
A fourth fan, meanwhile, chimed in: "I miss Tristan already hope to see him back at Christmas. Please grant us our Christmas wish. Looking forward to September," as a fifth wrote: "Please bring back Tristan for the Xmas episode."
There's no word yet on whether Callum will be back for the Christmas episode. His character, Tristan, will be absent from the new episodes due to him serving in the Royal Army Veterinary Corps.
What will All Creatures Great and Small series four be about?
The synopsis for the show was shared on the Instagram post, giving fans an idea about what to expect from the new series. It reads: "Returning to the beautiful Yorkshire Dales, the fourth series of All Creatures Great and Small continues with timeless tales and heart-warming stories, picking up in springtime of 1940 with change on the horizon for everyone in Skeldale House.
"James and Helen wonder when the right time might be to start a family, not knowing whether or not James will be called up to serve in the RAF. Tristan's absence is felt by all, but no one more than Siegfried who attempts to hold the growing household, and himself, together as he braves this new world. Mrs Hall and Helen’s friendship blossoms as they look to the future and new trainee veterinary student Richard Carmody arrives, causing complications in the house."
When will All Creatures Great and Small series four be on TV?
There's no specific date for All Creatures Great and Small series four, but they have confirmed that the six-part series will return to Channel 5 in the autumn. As with previous series, there'll also be a festive episode to look forward to.
For fans in the US, the show will land on Masterpiece PBS on January 7.