For Aidan Turner, being cast in Poldark felt like a risk. But, as the fifth and final series airs, there's no doubt it's paid off. The leading man talks to Georgia Humphreys about his favourite moments from filming, the lessons he's learned and saying goodbye to the role.

After four years of emotive drama, gorgeous Cornish backdrops and, ahem, the occasional scene featuring a topless Aidan Turner, Poldark is coming to an end.

Adapted from Winston Graham's acclaimed novels, the BBC One hit - written by Debbie Horsfield - stars Turner as passionate protagonist Ross Poldark.

The previous four series have followed the former military man as he desperately tries to turn around the fortunes of his late father's estate in Cornwall. But another large focus of the show has been his love life - in particular, his relationship with wife Demelza, played by Eleanor Tomlinson.

So, it's fitting that the final scenes Turner shot for the fifth - and last - series involved a day "in the bedroom" with Tomlinson.

"They weren't amorous, they weren't romantic scenes, we were just in the bedroom, you know?" elaborates the charming Irish star, 36, who's also known for The Hobbit movie trilogy.

"It was a great way to finish because it made sense that it was just us together, and us just having fun."

On feeling emotional on set, he recalls: "That was quite sad that day, because it was contained so you could sort of harness the emotion in the room.

"It wasn't like we were split up doing all these different things, different studios, running around and make-up changes and costume; it was just us together. That was quite sweet."

The previous series of Poldark covered Graham's first seven books. But the eighth (The Stranger From The Sea) is set 11 years down the line, when we meet Ross abroad on a special mission for the government.

Horsfield wanted to fill in the gaps, and look at how Ross ends up in that position - so she delved into history for the storyline, resulting in some exciting new characters.

Set in a new century - the 1800s - there is the promise of a hopeful future in series five. However, the past casts a long shadow over Cornwall, especially following the heartbreaking death of Elizabeth at the end of series four.

We will see Ross, who had resolved to put Westminster behind him, help out an old friend, which results in him feeling compelled to challenge the establishment and question his own loyalties to king and country. Meanwhile, Demelza must contend with dangers close to home.

But we can rest easy that the couple's famously turbulent relationship is solid this series - even if Ross "does bring another sort-of baddie into their world".

"He'll always do that, I think," reflects Turner. "He just has a natural attraction to menace, there's always something.

"But, together, I think they're stronger. It's when Ross is trying to carry the weight of the world himself that things tend to go wrong. I just think their dialogue is healthier now."

As for how Ross - who's in his early 40s in series five - has changed, the actor reckons his character has "grown up a lot".

"He's still impulsive and still has that gambler's streak in him and he still has an edge, but he's all round just a better person. Certainly kinder and better to Demelza, and just better at utilising his time - things we all get better at doing as we grow up."

How did Turner find filming this series, knowing it would be the last one?

"I don't know if it changes anything," he muses. "It's weird when you try to force a feeling, you try to make it memorable. It doesn't really... It's not that useful. There's still a job to do."

However, he admits it was sad seeing his co-stars finishing filming.

This must have been the case with Tomlinson; when asked about memories that stand out from shooting Poldark, straightaway he starts chatting about how much he's loved working with her.

He will also miss getting to shoot out and about in Cornwall (filming locations over the series have included the harbour in Charlestown, many beautiful beaches in West Cornwall, such as Porthcurno, and the cliffs along The Lizard peninsula).

"It's not often you can forget about massive television crews - sometimes a couple of units upwards of 50, 60, 70 people or more around on a day," he notes.

"But when you're out there galloping on a horse on the beach, or doing some of these scenes, you can't see them. And I've never had that before, where you feel like, 'God, I'm standing on the edge of a cliff here doing something that feels like I'm here on my own'.

"That's a nice feeling to have. And to remember that feeling and to bring it in and to use it other times when you need to have the feeling, and it's hard to have it because there's so many people around... Cornwall kind of gave me that.

"And to see that side of the world... It reminded me of home when I missed home because it just had that sense, and such gorgeous, lovely people who accommodated us."

Luckily, he did nab a couple of mementos from set to help him remember the role: "The hat came with me, definitely!"

With a laugh, he adds: "I took the kitchen table and the benches. I went big!"

Turner seems really genuine - he's jokey and laughs at himself a lot.

And he puts a lot of thought into his answers, particularly when asked what advice he would give himself if he could go back to the first day of shooting Poldark.

Looking back, he confides, he did feel "quite young to be anchoring a show" - and there was undeniably pressure for the show to be successful.

"It did feel like a risk at the time," he follows candidly. "We weren't sure if the show would have an audience, whether people would remember or care about the books or anything, and it just felt big to be in the centre leading this show. British actor, British character - would people buy it? Do people want an Irish guy doing that?

"So, there were nerves, but you just plough through it, you know? In that Ross Poldark kind of way. Grab the reigns and just go."

Poldark returns to BBC One, tomorrow at 9pm. Read Damien Love's review in The Herald on Sunday.