It's not every day that you hear parallels drawn between the Netflix series House of Cards and a Handel opera from 1709, but Máire Flavin is quite insistent. "I'm telling you," she says, resolutely tapping the table. "If you like Kevin Spacey in House of Cards, come and see the show, because Agrippina is the most psychologically manipulative woman. And Game of Thrones," she adds excitedly. "Joffrey is on our stage in Rachel Kelly's Nerone, I'm telling you."

Rachel Kelly, who is sitting across the table from her cast mate, nods enthusiastically. "It's true," she confirms. "I'm the opera Joffrey."

The pair, along with Padraic Rowan, are taking a lunchtime break in Dublin's Lir Theatre, where they are in the midst of rehearsals for Handel's Agrippina, the ancient Rome-set opera about a scheming mother's plan to install her son as emperor. It is the first time that the work has ever been staged in Ireland, in a co-production with Irish Youth Opera, Opera Northern Ireland and Limerick's Lime Tree Theatre. There's also a twist to the tale, as the centuries-old political drama is given a contemporary twist by director Oliver Mears, who has dressed his cast in sharp, modern suits and couture dresses.

The rehearsal room is packed with beautiful young things, including the aforementioned Flavin, who sings the title role. At 33, she is the most experienced of the three singers gathered around the table; fresh-faced Meath native Rowan (25) is a recent graduate of the prestigious Glyndebourne Young Artist programme in the UK, and Kelly (27) has just spent a couple of years on the Royal Opera House Jette Parker Young Artist Programme in London.

If you’re wondering how one becomes an opera singer in 2015, well, there is no straightforward answer. “The day of the fat singer standing in the middle of the stage is long gone,” says Dublin-born Flavin, who is based in the UK. “You have to look hot, you need to be fit, you are racing around the stage, you are expected to do anything: jump, climb, be upside down . . .”

Sean-nós singer

None of the three grew up with posters of Pavarotti and Maria Callas on their bedroom walls, but all found their way into opera eventually. “I wasn’t one of those kids who’s saying ‘I want to be on stage, I want to be an opera singer’ at the age of seven,” says Flavin, who had initially planned on a career in music therapy. “I saw my first opera at 16, but really didn’t fall in love with it until I started studying singing in college.”

Rowan, who trained at the Royal Irish Academy as a teen, initially studied international relations in college before pursuing opera, “because the diplomatic corps weren’t hiring,” he jokes. “My granddad was a sean-nós singer, but there was no opera in my family at all. My family knew I was musical because I’d be playing the piano in the house, but the singing just came about. I didn’t really plan it. It just happened.”

On the other hand, Kelly, who was born in Cork and raised in Dublin, seemed destined to be an opera singer given her classical-oriented family background – although she claims that pop music was more her bag as a kid. “It was always in my ears, but I suppose children don’t naturally love opera,” she says. “I loved Disney singers and I loved Whitney Houston and things like that, but I suppose as your voice is trained, you see what your vocality is more suited to. Mine was definitely more suited to opera.”

All three agree that the life of an opera singer is no cakewalk; natural talent is only one aspect. “Of course, you have to have the voice; that’s building block one,” says Flavin, the product of four different institutions of education. “But it is a building block. If you don’t have the ambition, the passion, the drive and the work ethic, forget it.”

The biggest misconception about opera is not only the jetsetting lifestyle – “more like economy on Ryanair,” Kelly grumbles good-naturedly – but the notion that you are earning megabucks from the beginning of your career.

“It’s a very slow burn. The best way to do it in this industry is slowly,” says Flavin. “If you look at something like ballet, they’re done by the time they’re in their 30s, whereas in singing terms – because the training is so intense and your larynx has to mature – you’re still really moving towards the peak of your career nearer to 40.”

Personal sacrifices

Apart from the financial sacrifices, there are the personal ones, too. The life of an opera singer, as they tell it, is often lonely. It entails lots of travelling to where the work is and living in strange cities for months at a time.

“You have this unnatural environment where you form these very close, intense friendships in a short space of time,” says Kelly. “Affairs happen, or when the production finishes and you feel you have this very deep friendship, you go back to your normal life and it’s very strange.

“I’m only experiencing this for the first time, because I’ve been on a contract in London. People can say to you, ‘This career is hard and you’re going to be away from people’, but I’ve always had this opinion of myself that I’m very independent and I’d be fine. But I’m getting married in two months and miss my fiance so much. It’s kind of dawning on me how difficult this career is going to be.”

With so much of their lives taken up by their careers, you might imagine there is little time for outside pursuits, although Kelly claims an interest in bouldering and hiking and Flavin is an advocate of yoga. Still, there is little time for vice. Opera singers apparently live the kind of virtuous lives that causes spasms of shame in mere mortals. Coffee? It’s a vocal irritant. Alcohol? Nope. Smoking? You must be joking.

“Your instrument is your body and everyone’s body is different, so it is an individual thing,” says Flavin, shrugging. “I personally am not the kind of singer who can go out on the piss and then sing.”

“On my ideal day, I’ll get up around 7am and work out for an hour,” Kelly says. “I’ll have a nice breakfast, but I will have coffee, even if it’s an irritant. I’ll go to rehearsals all day and maybe have a little nap if there’s a show that night. But fitness is huge. I do love red wine, though, and it’s not so good for singing. It’s about balance. Acid reflux is a big thing, because if you have it, you might not be able to do a show the next night. So you have to be strict and not have that KFC on the way home.”

Rowan sums it up. “There’s no such thing as a welfare system for opera singers,” he says. “You sing or you don’t get paid.”

• Agrippina runs nationwide from September 8th-19th; see irishyouthopera.ie for full listings

THREE OPERAS TO SEE: EXPERT RECOMMENDATIONS

Máire Flavin: "Mozart operas are very accessible and are very easy to get into, like The Marriage of Figaro. In terms of something that really hits home, for me it would be either La Bohème or La Traviata, which was the first opera I saw. The final chords towards the end are gut-wrenchingly emotional, and that is what the best operas will do."

Padraic Rowan: "One of the pieces that I did which completely struck me was Billy Budd by Benjamin Britten. It's an all-male cast and there's this battle scene where you have 60 male voices on stage, all singing in unison, drummers going 90 on the stage with you. It's the most euphoric I've ever felt on stage."

Rachel Kelly: "Puccini's Tosca is such an amazing story, with such a tragic ending. She sings one of my favourite pieces of any opera, too: Vissi d'Arte, or 'I lived for my art', which resonates with any singer."