Ed Westwick is a bad man. Consider the charge sheet. He’s seduced and manipulated every woman with a pulse in the Upper East Side of Manhattan. He stabbed a rival’s best friend in Verona. He was briefly a serial killer, then a ferocious Cuban gangster terrorising the East End. Now he sells double glazing. Oh, Westwick is bad news alright. But then the devil always gets the best lines.

If you’ve ever watched Westwick on screen – big or small – you’ll know a good line isn’t wasted on him. Most famously as Chuck Bass in the wildly popular TV series Gossip Girl, purring bon mots such as “Whoever said that money doesn’t buy happiness didn’t know where to shop” while draped in a $1,000 scarf. There are worse ways to make your name.

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He should enjoy some zingers in his latest project. Written by Damon Beesley, co-creator of The Inbetweeners, White Gold portrays the cutthroat world of double glazing sales in 1980s Essex. Westwick is Vincent Swan: charismatic, amoral and fiercely on the make – “a bit of an animal”, according to the actor.

“He’s definitely kind of the alpha male, leads the pack, is driven by his ambition. He wants more, and he doesn’t care how he gets it.”

Swan is more rogue than villain, but his blind ambition leads down some dark avenues.

“There’s some pretty deplorable behaviour,” confesses Westwick, before adding wryly, “I sound like a nun right now.”

He gives an example of such behaviour – “Am I allowed to reveal this?” he asks his publicist – and it’s indeed pretty deplorable, the type of act puerile teenager Jay from The Inbetweeners would boast about but be unable to pull off. No spoilers here.

Speaking of Jay – as well as Beesley, Inbetweeners alumni James Buckley and Joe Thomas star as Swan’s colleagues, both sporting questionable facial hair. According to Westwick, the humour is similarly raunchy but viewers should expect more dramatic, complex storylines than tended to be found in the superbly adolescent E4 comedy.

“Everything people loved about The Inbetweeners, they’re going to see within this, and then there’s a lot of new elements as well.”

For Westwick, it was a case of right show, right time. He’d never properly done ‘straight comedy’, and both he and his agent were immediately attracted to the script.

“We thought it was pretty hilarious, and a really interesting move.”

He’s a relaxed presence, Westwick, with a dryness of humour that verges on the sardonic, and a languid delivery one might reasonably describe as a drawl. His arrival in the Square Mile studio prompts an excitement among the female staff usually reserved for rock stars or Second Comings.

Although he dons the threads for our photoshoot, his body sports an impressive array of ink – most notably a topless woman on his upper right arm.

“This was a girl who was already there,” he says of the lady in question. “I got 1936 tattooed [underneath her] because my grandmother won a contest called Miss Lovely Legs 1936. So my grandmother’s topless on my arm,” he deadpans. (Westwick deadpans a lot.)

One of the refreshing aspects of interviewing him is the sense of a hinterland: that there’s a lot more that interests Ed Westwick than simply being Ed Westwick. His answers are always considered, and often migrate into unexpected areas. You can sense his mind moving as he speaks.

So ask his favourite writers and he replies, “Hemingway”, then describes the book he’s currently reading – Midnight in the Garden of Good and Evil by John Berendt – and then that book’s setting of Savannah, Georgia segues into a meditation on the Deep South.

“There’s that charm about the south that I really, really quite love. I’ve been lucky enough to visit some of the cities, but from reading the book I want to go to Charleston, and I want to go to Savannah. These kind of old-world Southern cities that are perhaps kind of the same as they were 100 years ago.

Similarly, bring up the possibility of James Bond – “You wouldn’t say no to that, would you?” he murmurs. “You wouldn’t say no…” – and soon you’re discussing the evolution of the spy series into the 21st century.

“As a society we’ve developed with technology and stuff like that, the world has become a more complex place, therefore the stories have become more complex. We, as people now, either love violence or hate it.”

There is violence aplenty in his other TV series of 2017, a spinoff of Guy Ritchie’s Snatch. As with the original film (and all early Ritchie) the action concerns an eclectic cast of East End chancers – Hasidic Jews, gypsy boxers, loquacious cockneys – crossing and double-crossing one another while attempting to make a dishonest buck.

Westwick is Cuban gangster Sonny Castillo, over from Miami to take care of the mob’s nefarious London interests. In the trailer he fires a machine gun after Rupert Grint while sporting a kimono and a perm. It looks a blast.

“I did that one because I was such a fan of the film,” says Westwick. “I was like, I need to be involved in this show. It’s so well written – Alex De Rakoff [the show’s creator and director of Dead Man Running] has brought the world alive again in such a fantastic way.”

Although his hair swerves the 1980s in White Gold, the Snatch perm was actually Westwick’s idea: “I looked in the mirror and I went, how am I going to pull this off? So I went, give me a perm. That’ll do it. So I’ve got a perm – slightly blackened – and one of those little beards. I look like Drake.”

The machine gun must have been a bonus?

“It’s always a plus. Especially when you’re wearing a dressing gown.”

You’ve got to do things you love, right? Especially in this game, because if you start doing the things you don’t particularly love then it will start to show. I don’t want that.

Of course, Westwick’s big break came on TV. Gossip Girl chronicled the lives of a clique of stunningly attractive teenage socialites and their many indiscretions, normally involving each other. Unlike its more wholesome predecessors, such as One Tree Hill, the show wallowed in its immorality – ‘Every Parent’s Nightmare’ boasted a poster for Season Two – and displayed a relish for conspicuous consumption that would make Jay Gatsby swoon. It ran for six seasons of increasingly lurid storylines before finally ending in 2012.

As malevolent playboy Chuck Bass, a teenage Mephistopheles whose thirst for hedonism was matched only by his appetite for self-destruction, Westwick won fans around the world. (4.5m of them follow his Instagram.) Did he ever worry Chuck would cast a shadow over the rest of his career?

“Worry’s not the right word,” he begins, speaking more thoughtfully than ever, “because that’s not something to worry about. It’s an interesting challenge, but never one I ever thought about too much. At the end of the day I was very young – I was 25 when we finished it. You know you’re going to change visually, you’re going to mature, and you’re going to learn different things.

“In most cases I’ve done the things I wanted to do that I felt were going to depart from [Gossip Girl] anyway. Of course there’s been other things down the road that I would have loved to have got that I haven’t got, things that may have helped earlier, but it’s fine. Where I’m at right now I’m very, very happy.

“You’ve got to do things you love, right? Especially in this game, because if you start doing the things you don’t particularly love then it will start to show. I don’t want that.”

He starred in Chalet Girl with Felicity Jones – “She’s an incredible person, an incredible actress” – of Star Wars: Rogue One fame. Has he explored the blockbuster route?

“Of course. I work in a very competitive industry, and there’s been loads of things that I would love to have been a part of, and either was too busy or I didn’t get the job or whatever. That’s just what happens.”

He’s still frequently recognised as Chuck Bass, and will be for a few years yet. The likes of Netflix have ensured the popular TV shows of old can be consumed by new generations – a point Westwick raises.

“People can enjoy that show ten years down the line. I haven’t seen any of it in a long time but I mean it’s got to be somewhat timeless – it’s not dated or anything just because it started ten years ago.”

He notes how the central concept of Gossip Girl – a mysterious blogger who updated young New Yorkers on the latest juicy scandal – anticipated the rise of social media and the impact of the mobile phone. “It was actually ahead of its time in a way.”

What Westwick doesn’t mention – and only occurs to me after our interview – is that another modern phenomenon was foreshadowed by Gossip Girl. The obsession with wealth, the glitz and glamour, the Manhattan setting, and yes, the debauchery and sexual transgression – the show might as well be Trump: The Teenage Years.

Inevitably the show ran out of inspiration long before the end. In the final episode Gossip Girl is revealed to be aspiring writer Dan Humphrey, a choice laden with implausibility. Did the cast know of this twist in advance?

“No, I think they made it up on the last day,” says Westwick cheerfully. “Nobody cared at that point. So it was literally eenie, meenie, miney mo, I think. So there you go.”

Our May issue hits the stands on Wednesday 24 May 

Would he be open to a reunion? “I don’t think so. I think we had a lovely, lovely time, we were very, very lucky to get that run, and we enjoyed it and it meant an immense amount. I think people have moved on. But saying that, I’m a fan of Friends. Who doesn’t want to see a Friends reunion? From my audience-member side, I’d want to see it. But when you’re involved in it, and it’s your work, and that was that… It’s funny.” He trails off but the insinuation is clear – let the past be.

So then what of the future? When interviewing an actor like Westwick, established as a name but still relatively early into his career, it’s always interesting to venture into the hypothetical. For example, who would be his dream co-star?

“I’d love to work with Gary Oldman, that would be awesome. I’m a massive fan of Gary Oldman. Very cool guy.”

Romantic lead? “Meryl Streep. She’s fantastic. If I had to just pick someone I wanted to work with... Nah, I don’t know. I don’t know. I don’t want to say someone and then run into them and be freaked out.”

Director? The answer is immediate: “I would love to have worked with Anthony Minghella.” British director and screenwriter Anthony Minghella died of a haemorrhage in 2008. A teenage Westwick appeared in Breaking and Entering, which proved to be Minghella’s final film as a director. “I’d have loved to have worked with him again. What a talent. His films are some of my favourites – Cold Mountain, The Talented Mr Ripley.

The choice isn’t solely down to Minghella’s artistry. “It’s more, you want to see someone again who was so significant in your life. Because it happened so early on [in Westwick’s career]… You just kind of wish you might have been able to work with him again.”

Every year is different. I’ve had quiet years, I’ve had packed years, and I’m sure it will be the same as long as I choose to do this

Unprompted he volunteers Martin Scorsese as an alternative – “you’ve got to go with your big favourites like Scorsese, haven’t you?” – and later cites Hong Kong director Wong Kar-Wai (In The Mood For Love, 2046) as another inspiration. But the conversation returns to Minghella, and the experience of filming Breaking and Entering with the likes of Jude Law, Juliette Binoche, Ray Winstone.

“It kind of set the tone for me. These people were so nice, people at the top of their game, and it just kind of set a benchmark.

“It was a very important lesson that was instilled in me at a young age, and it gave me a sort of compass upon which to work from. A professional standard perhaps…” For a few seconds his mind seems to drift before snapping back into the room. “But that’s not going to be able to happen again, is it?” he says briskly. “Marty, if you’re listening…” He leans into the voice recorder.

Acting isn’t Westwick’s only creative pursuit. He fronted rock band The Filthy Youth and, more recently, has been putting pen to paper – although, like many aspiring writers, he’s coy on the specifics.

“Little bits and pieces but not anything that’s considered a significant amount of work or I’d put in a specific category. I’ve got a couple of things that I’m developing – films and some other content – that I’m not really sure exactly what it fits into.

“It’s an area that fascinates me. I’m a big fan of the written word – particularly how writing and developing stories changes from, say, a book or a short story into a script or a play or something like that. It’s something that I think helps as well when you’re an actor, trying to understand the writer’s words. The more you can understand where the someone’s coming from, the more it helps you to become embedded in a piece of material.”

There is also a passion for travel, as you might have surmised from his fascination with the Deep South. “I have already done quite a bit of travelling, but it’s not a tiny world. There’s a lot of places that I want to go to.” He’s off to Venice on the Orient Express, and also wants to ride the famous old train to Russia at some point in the future.

Trains even permeate Westwick’s personal TV tastes. “I’ve been watching a lot of Michael Portillo doing the railways. That’s a very nice programme, isn’t it? Quite gentle. I like it.”

It’s a pleasingly unexpected citation, as is his response when I ask him what type of show he’d like to present.

“I thought what Tom Hardy was doing was quite interesting. Did you see him reading children’s books?” (He’s referring to CBeebies Bedtime Stories, a programme which has attracted the likes of Hardy, David Tennant and James McAvoy to lull the nation’s toddlers –and their mothers – to sleep.) “I really like it. So I’ll read you a book, kiddies.”

Children’s narrator aside, the next few years should be big ones for Westwick. He’s too talented an actor not to land a major film role, especially as he turns 30 and reaches the prime years for a leading man. Or perhaps he’ll find another vehicle in what he terms “the golden age of television” – the next small-screen epic from the likes of HBO or AMC. After more than a decade in the industry, Westwick knows the merits of the long game.

“It’s an uncertain career path, but that’s also the exciting thing about it as well. Every year is different. I’ve had quiet years, I’ve had packed years, and I’m sure it will be the same as long as I choose to do this.”

The future looks golden for Westwick. The bad boy’s done good.

White Gold premieres 24 May on BBC2.

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