Back-stabbing reality hit The Traitors is such a perfect format that television producers surely tinker with it at their peril. Yet that is what the BBC has done with the fourth season of the British edition of the show (fifth if you include the recent Celebrity Traitors).

Presumably worried that the novelty is starting to wear off, they’ve introduced a new gimmick: a “secret” traitor, in red robes, who operates the marionette strings off camera (their identity concealed from viewers and contestants alike).

Setting aside the point that all traitors are secret by definition – otherwise they wouldn’t be traitors, they would be villains – the innovation has undoubtedly altered the chemistry of the series.

It has also yielded its share of television gold – as proved by the priceless expression on the faces of traitors Rachel (a 42-year-old marketing executive from Co Down) and Stephen when they discovered that the secret puppetmaster was Welsh local government official Fiona.

They gasped, they gurned, they laughed at the impertinence of their dark overlord – whose job it was to present the actual traitors with a shortlist of murder victims each night. A week into the latest season, the twist sprinkled on some much-needed post-Christmas spice.

That said, you do wonder if the “Secret Traitor” mechanic would work on the Irish edition. Season one on RTÉ was a huge hit – the final drew a blockbusting 750,000 viewers and gave the country the overnight boomer celebrity we didn’t know we needed in hug-averse former prison officer Paudie Moloney.

But it worked in part because the basic idea was so straightforward: send a random collection of people from all walks of life to Slane Castle in Co Meath and watch them merrily knife one another in the figurative back. Introducing a secret traitor would complicate a formula that has the virtue of being simple and which gave traitors such as Paudie and Nick carte blanche to weave their deceptions.

Backstabbing, cliques, lies … The Traitors Ireland is every office you’ve worked in ]

Imagine how much less dastardly they would have been had they been required to always glance over their shoulders, wondering who in the castle was pushing their buttons off camera. It would have brought an extra layer of strategy – but would it have been any more fun, for them or us?

Contestants James and Rachel in BBC1's The Traitors. Photograph: Euan Cherry/PAContestants James and Rachel in BBC1’s The Traitors. Photograph: Euan Cherry/PA

The latest UK Traitors had several other shocks up its sleeve. Contestants Judy and Roxy are mother and daughter, while Ellie and Ross (ejected in a surprise Wednesday night round table) were a couple. Yes, RTÉ’s Traitors has already gone there with the casting of secret father and son, Paudie and Andrew.

But with three distinct gimmicks this season, there is evidence that the makers of the British version are terrified of the blueprint going stale.

RTÉ need have no such worries. The Irish Traitors was a masterclass in skulduggery and rug-pulling. Whether it was Paudie hiding in plain sight as a traitor or the bromantic duo of Nick and Ben high-fiving each other at every chance, the show was a clean-running engine of subterfuge and double speak.

Bringing in a red-robed secret traitor would only complicate matters – and, as everyone in Ireland knows, there’s nothing worse than a party-crasher with an over-the-top dress sense.