All Creatures Great and Small star thinks Tristan and Charlotte marriage could be on the cards after huge romantic scene

Tristan and Charlotte's relationship is continuing to go from strength to strength in All Creatures Great and Small.

After the couple instantly hit it off in season 6 of the period drama – when he answered a call to examine her beloved horse – each meeting that followed was a success, including Tristan winning over her father despite the class barrier between them.

But it's in their toughest moments when their connection is undeniable – hinting they're in it for the long haul.

During this year's Christmas special, Tristan's PTSD resurfaces as he admits he can't stop thinking about the horrors he witnessed while serving on the frontline, including the death of his best friend.

Much as he wants to embrace the festivities, he simply isn't able to shut off the noise. But instead of running in the opposite direction or telling him to get a grip, Charlotte not only stands firmly by his side, but also gently encourages him to open up, knowing it's part of the healing process.

Read more:

• All Creatures Great and Small gets major update on its future
• All Creatures Anna Madeley responds to Siegfried kiss: 'We've no idea where this goes'

It was that moment, more than any other, in which it became abundantly clear they're not just here for a good time, but a long time. And shortly afterwards, in a supremely romantic scene at the Christmas tree farm, surrounded by firs, Tristan told Charlotte he loved her – and she said it back.

"I think she's come into his life at a time when he just really, really needs her," Calum Woodhouse told RadioTimes.com, explaining why they work so well – and what makes Charlotte different to every other woman he's been involved with.

"I think they've got a great chemistry and they get on really well. And that would have been similar at any point, but Tristan, right now, needs someone who is sympathetic and understanding to what he's been through, and is very much still going through. And Charlotte is just that, in spades.

"Not only has she been through some of it herself [given her own service], but she's just a very kind character who allows Tristan to, in his own time, and in his own way, find his way back."

Woodhouse also said Charlotte "loves Tristan for who he is, not for who he once was, or could be again".

"It's really sweet, and it's a joy to play with Gaia [Wise], who's who plays it wonderfully."

So, that begs the question: does Woodhouse think there could be wedding bells in Tristan and Charlotte's future?

"I think so," he nodded. "I think they're a really great pair."

He then went on to compare that relationship to what's bubbling away between Siegfried and Mrs Hall.

"It's an interesting one, because, obviously, the big fan response to some of the love stories of this series is that people really, really want Siegfried and Mrs Hall to end up together, who are from very different backgrounds," he expanded.

"Mrs Hall is the housekeeper, and Siegfried is the man in charge. So that's maybe a dynamic which wouldn't have normally been done.

"And then on Tristan and Charlotte, she's from extreme wealth and he isn't. And it's sort of the exact sort of opposite of Siegfried and Mrs Hall. So it's just funny that you've got those two playing sort of in tandem.

"But I think they [Tristan and Charlotte] have just got really great chemistry. So it'd be interesting to see how that's further explored in the next series."

All Creatures Great and Small seasons 1-6 are available to watch on 5. You can order James Herriot's All Creatures Great and Small from Amazon.

Add All Creatures Great and Small to your watchlist on the Radio Times: What to Watch app – download now for daily TV recommendations, features and more.

If you're looking for something else to watch, visit our TV Guide or take a look at the rest of our Drama coverage. For more TV recommendations and reviews, listen to The Radio Times Podcast.