The good news – or maybe it's the bad news if you have a particular penchant for cruel, entitled, arriviste, Victorian landowners with a sneering attitude towards the lower orders; there's probably an app for it: Hothistoricalsnobs, maybe, or Nastieswhoyou'ddothenastywith – is that Jack Farthing isn't very much like his Poldark character.

I know, I know. It's a terrible disappointment. You want your actors who play villains in popular Sunday-night telly dramas to be proper method. You know the kind, drinking tequila and snorting snuff for breakfast and using ragged urchins to clean their iPad dock. With their tongues.

But the sad truth is on what we will call the George Warleggan scale of caddishness, Farthing is frankly disappointing. I know. I've done the tests.

How much like George are you, Jack? For example, when was the last time you were cruel to an old lady not necessarily called Aunt Agatha?

"I haven't ever done that," Farthing says. "Not as recently as George has anyway."

The Corn Laws. For or against? "George and I differ on all sorts of things like that."

Have you ever attempted to get anyone executed recently, Jack? "Not that I can disclose."

And are hats inherently a sign of villainy? "I don't know about that. I don't think so. George does use his for a few extra inches. He likes the height it gives him."

Well, do you wear hats? "I have been known to wear caps, it's true. But I don't think it makes you more villainous."

So, basically, Farthing is nothing like Poldark's favourite villain in the slightest. Which makes him what? Oh yeah, an actor.

The truth is, that in opposition to the characteristics of the role that has made him famous, and a name that is surely a stick-on for a minor character in a Charles Dickens novel, Jack Farthing is in reality a polite, pleasant, slightly tongue-tied, rather reserved, handsome, high-cheekboned young man who doesn't abuse old people or hold grudges against good-looking, headstrong but politically progressive types called Aidan who take their top off a lot.

Wednesday morning. North London. Farthing is just back home from the Herald Magazine photoshoot. Paint us a picture of your surroundings, Jack. "It's pretty standard. Sofa, table, a bit of a mess."

Are there dirty dishes in the sink? "At the moment, no."

And is the mess all yours? "I live with my girlfriend." Hah, subtly shifting the blame there. Maybe he's not totally lost to villainy.

Farthing is almost finished with Poldark. Almost. As you read this the fifth and final series of the BBC's much loved Cornish drama is about to air, but when we speak in April Farthing still has some post-production work to do, some ADR (get me, knowing all the lingo).

He hasn't quite slipped out of the shadow of Poldark yet. "I think it will be strange when the last one airs in the summer. That will be a definitive full stop. At the moment, it's kind of lingering. It doesn't feel quite like I've said goodbye to it. But when that time comes it will be odd."

Filming wrapped in February. Farthing was on set until the final day. He left early. "As ever with these things there was n not some big climax. The last week is always like, 'Oh God, we're running out of time.' There's lots of loose ends to tie up.

"I think in the first schedule they had it so there was this big group scene which they were going to shot last but inevitably things got in the way. But it was nice, it was celebratory. It wasn't too sad. It was a sense of achievement."

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Well, indeed. Poldark, a proper period melodrama full of beautiful people suffering terrible things, has been appointment television for roughly five million viewers since Debbie Horsfield's adaptation of Winston Graham's novels started to air back in 2015.

It has been something of a dream job, Farthing says. "It was a total joy to film. They were lovely, lovely people. I made some friends who I will always have as friends and it's nice of being part of a family that is making something and to feel you're right at the heart of a show and to have a relationship with the writers and execs. I will miss that definitely."

And now we've reached the end. So, Jack, nothing to lose. Give us some spoilers for the last series. Do aliens land in Cornwall? Does Madonna make a guest appearance? Does George get his comeuppance?

"Three unlikely suggestions."

But you haven't said no.

He laughs. "I can confirm that Madonna is in."

No spoilers then. What he will say is that the range of the show has grown again. "We see more of the characters and more of the world. They've been stretched as humans. We see more of them and that's definitely true of George. You see different sides to him.

"For George there are new challenges. He ended the last series crying over the death of his wife Elizabeth, played by Heida Reed; this tragic, traumatic thing. And so, this series - particularly the first chunk - is about him in recovery from that really. When we first see him, he looks like he's all back to normal but fairly soon we realise he's absolutely not."

If he's honest, he says, he will miss George. "I've spent a lot of time with him and I've tried to work out how he ticks for the five years. I probably see more good in him than anyone else. But that's probably my job as an actor."

Do you have to see the good in him to play him? "It's not necessarily the good, but you need to see the reasons. You need to justify the behaviour to yourself, otherwise you can't really be true to it.

"You don't have to agree with everything they think or say," he adds. "During this series George expresses some very dubious views about slavery but he is saying it for a reason, and I have to understand that and be able to justify that to m myself."

Are there George Warleggan groupies, Jack?

"Oh gosh, I wouldn't know."

Come on. You must have had letters.

"I have had some, that's true, yes. People are much nicer about George than I necessarily expect them to be. I haven't received bricks through the windows or anything like that. Obviously, there's a bit of loving to hate him."

Farthing has had other memorable parts. He played John Lennon opposite Sheridan Smith in ITV's Cilla biopic and he was in last Christmas's Agatha Christiethon, The ABC Murders, but it's possible that George will be the role that defines him for a while. He's looking forward to show that there is more to him than high cheekbones and snobbish hauteur.

"I feel I'm back to being an actor again as opposed to being in one show where you sometimes feel that you're ... Not limiting yourself, but stretching one set of muscles. It's quite nice to challenge yourself in different ways."

That all starts a few days after we talk. In a matter of days, he says, he starts shooting a new movie, Love. Wedding. Repeat. Did I mention he’s shooting it in Rome? Nice work if you can get it.

“I’m going on Monday for a nice little comedy that will be extremely different to Poldark and that’s one of the most attractive features for me. It’s totally nice to jump into a different world. It will be fun. Lovely group of people, nice ensemble comedy and five weeks in Rome. That won’t be too much of a struggle.”

Yeah, rub it in, Jack. He won’t be totally escaping the shadow of Poldark though. Because one of his fellow cast members in this new film is none other Eleanor Tomlinson, aka Poldark’s better half, Demelza.

“Yes, by wonderful coincidence. I think we will have more scenes in this film than we had together in the same show. So that will be nice.”

Some random quickfire questions for Jack Farthing:

What was the last thing you loved as a viewer yourself?

"I've just watched Sharp Objects with Amy Adams. It was pretty extraordinary and harrowing but brilliant."

What is your party trick?

"I wish I had a party trick."

So, you just sit in the corner moping?

"That's me. That's my trick. The mope."

What makes you angry?

"Selfishness. That makes me angry."

What makes you happy?

"So many things. My friends and family ..."

He thinks for a moment and then declares that a boring answer. Well, what else then? "Good food makes me happy. I could eat Japanese food for the rest of my life."

What is your bad habit?

"I probably worry too much. Don't we all?"

Born in 1985 in London, Farthing is the younger brother of parents who were both doctors. When he started messing around with drama at school did they never say to him “get a proper job”?

"No, they were wonderful. They've always been wonderful. They were totally supportive. They could see that my love for it was the main driving thing."

What was the teenage Jack like then? "Wow, what was I doing? I was at school doing bad plays probably."

Well were you sweet, loud, surly, sulky? "The right cocktail of sulkiness."

Really? What was your music of choice, then? "Definitely some sulky music. Definitely The Smiths. The Smiths were kicking around. They're the definition of sulky, aren't they? I still adore them.

“So, I was probably a bit sulky, but I don't think I was abnormally sulky."

Farthing went to public school. Westminster. Obviously, in my council estate-raised head, I tell him, public school is straight out of Tom Brown's Schooldays - school bullies, fagging, all that stuff.

"It wasn't that,” he corrects me. “I had a wonderful time at school. Westminster's different because it's bang in the middle of London. It's not a bubble. It meant that he people who were there were broader in range and types than you might expect. I had a great time there."

It's where he started acting. At the age of 10 he was doing grand school plays, "stupidly big-scale productions, big historical things. I remember we did of A Tale of Two Cities, mad, big, epic, stuff."

Hmm. Grange Hill it was clearly not.

Was acting the only career he ever considered? Are there other Jack Farthings in some parallel universe living very different lives? "There was a while when I flirted with music and I was in a terrible band or two."

What were they called? Name names. "I can't possibly do that because somewhere lurking in the depths of the internet they might still exist. I couldn't possibly let myself in for that."

Well, at least tell us what you did in the band? "I was playing guitar, singing. Front man, yes. I know it sounds ridiculous. I couldn't be further from a front man. It was good fun.

"But probably it was acting that was the thing that fired me up most and that was the thing I was most excited about doing. It was from very early on. Like nine, 10."

He studied at Lamda, left early to take a job at the Globe playing Benvolio in Romeo and Juliet. "I still remember walking out onto that stage for the first time and thinking, 'I'm being paid to do this.' That was definitely special."

It still is. Jack Farthing is not a villain. He’s an actor. He’s more than happy about that.

“It’s a ridiculous situation. Not many people are able to follow their passion and make a career of it. So, it’s not something that ever leaves me that feeling. It’s always one of excitement and feeling quite jammy.”

Jack Farthing is “quite jammy.” There are worse things to be.

The last series of Poldark begins on BBC1 on Sunday, July 14 at 9pm.

Photographs Paul Stuart. Grooming by Charlie Duffy using Harry’s.