This article includes some discussion of the first episode of The Traitors, including format changes, but does not contain major spoilers such as who the new traitors are or who gets murdered or banished.

The Traitors has returned to our screens, with its usual combination of murders, missions and midnight meetings. The number of contestants this year has risen to 25 – ranging from a former British diplomat to even a member of the clergy.

“I just love a good murder,” says the priest, Lisa, in the opening episode, revealing that she’s “had a chat” with the man upstairs about the ethics of taking part. But, she concludes: “Any self-respecting murder mystery needs to have a priest in it.”

Wednesday’s launch saw her joined by a retired opera singer, beautician, landscaper, swimming teacher, window cleaner, financial investigator and British Army soldier.

But although the players are different, and a few key changes have been made to the format (more on those in a sec), the show’s core principles remain.

“The absolute beauty of the Traitors is the game itself,” says presenter Claudia Winkleman. “I get messages all the time from people playing it in theatres, on film sets, in schools, even a Traitors wedding – I agree, too much.”

The presenter says she feels “completely terrified” by the launch of series three – fearful both of accidentally revealing spoilers and also whether audiences will like the show as much as the previous series. “I don’t exhale until January 24th,” she jokes.

“It is such an honour to be in that round table and to see how it unfolds, so I feel incredibly lucky and love it, and you just don’t want people to be disappointed, because the people who like [the show] are so vocal.”

The Traitors is one of the BBC’s biggest success stories of recent years. The first UK series was watched by a total audience of around five million, the second by more than eight million.

A true watercooler hit, it is one of the few shows in the streaming age which viewers feel they are watching at the same time as everyone else.

Several tweaks have been made to the central format this year, although it’s not yet clear how big an impact they’ll have.

One early twist in this series is somewhat reminiscent of the first, as three contestants are made to leave before they’ve even entered Ardross Castle in Inverness.

“When they turn up, they assume they know the way the game is going to go, and it is our job to explain that it isn’t,” Winkleman says of the changes.

“There are twists throughout, but they have to be different from series one and two. They’ve come to hopefully walk away with up to £120,000, but also to play a game, and I like the fact that they don’t know which way it’s going to go.”

It remains to be seen whether there might be a way back later in the series for the contestants who sacrificed themselves, as there was in series one for Amos and Kieran, the two players who were ejected at the castle doors.

Perhaps more significantly, Winkleman tells the new crop that the few contestants who make it to the final this year will no longer reveal whether they are a faithful or traitor as they are banished.

Instead, the remaining players will have to rely solely on their instincts about whether or not any Traitors are left, ultimately making their decision of when to end the game harder.

“It underlines… the main body of the show, which is trust and gut instinct,” Winkleman says. “You’re going to like the end, I hope, that’s all I can say, it throws it all on its head.”

It’s hard to predict how this might impact the final in practice. Had this rule been in place last year, it may actually have made it easier for Harry to win, as Andrew’s last-minute attempt to bring his fellow traitor down before being banished might not have aroused as much suspicion with Jaz.

Critics were broadly positive about Wednesday’s series launch, but some noted the show will have to continue innovating to keep things fresh.

“The Traitors, like its players, must constantly adapt, so the brutality must be upped,” said Carol Midgley of the Times.

“But I think it needs to twist the screws a lot more than this if it wants to hold a candle to last year’s show.”

The Independent’s Nick Hilton noted: “This third season of The Traitors is, naturally, more self-aware. Contestants know the various gameplans employed, know that the producers keep several cards up their sleeves.

“There is a sense that competitors want to guarantee more screentime by playing games within the games, presumably at the encouragement of the production team.”

But the Evening Standard’s El Hunt said: “All of the key ingredients are already in place. Though it’s initially hard to get to know 22 contestants, the leaders, court jesters, and potential threats are all beginning to emerge already. A winning formula strikes again.”

In the opening episode, one of the new contestants shrewdly suggests that more of the Traitors this year might be women, after those in the last series were predominantly men.

“There is a little bit of that, and you’ll see how it works out for us,” Winkleman tells journalists, giving nothing further away.

But, the presenter adds, she does not choose the traitors by herself. Instead, she explains: “We talk to all of them, and then six of us go up to a room, the brilliant casting people, and we get through seven packets of biscuits.

“I’m the smallest voice in the room, but you decide while having had those chats who it’s going to be.”

There are two sisters taking part this year, although they are open from the beginning about their relation to each other – unlike some contestants in previous series.

Their casting is part of the wider effort to make sure the show is always slightly different, with new people, new personality types, and new relationships.

“In any entertainment format, you can’t repeat,” Winkleman reflects. “You want to give the people who are playing and watching, something new. So yes, two sisters, let’s see how that works.”

Some of the latest crop have come up with innovative new tactics – one contestant is attempting to maintain a fake Welsh accent throughout her time in the game.

“I get it, if you’re playing a game of deception, why not start at the beginning?” Winkleman reflects.

The presenter’s biggest fear is accidentally giving away the traitors’ identities while filming the roundtables. “I am absolutely paranoid about ever looking at the traitors, so I sort of look just above everybody’s head.”

By her own admission, Winkleman gets emotionally involved in the series and keeps in touch with contestants after they’ve been on the show.

“I love them, each and every one, all of them,” she smiles. “I was texting Maddy from series one the other day, I sent a message to Charlotte’s aunt.

“Matt from series one wanted to show me his new skill – sorry, that sounds like code, it was skateboarding. Aubrey sends me pictures of his living room.

“But I stay in touch with all of them because I’m so grateful to them for playing the way they do. And these people [in the new series] are extraordinary game players.”

The first two episodes of The Traitors are now on BBC iPlayer. The rest of the series will air at 21:00 GMT on Wednesday, Thursday and Friday nights.