Hannah Fry Reveals Her Mathematical Strategy for Catching Traitors After Bringing a Spreadsheet Into the Castle
Mathematician and broadcaster Hannah Fry entered The Celebrity Traitors with an unusually methodical plan to expose the contestants hiding behind the Traitor role. Armed with a spreadsheet, extensive notes and a strategy inspired by Alan Turing, she intended to use mathematics to narrow down the possible identities of the show’s secret saboteurs.
But Thursday’s episode delivered an unexpected twist. After James Blunt predicted that the Traitors would recruit their biggest threat, Hannah found herself joining Maya Jama and James Acaster as a Traitor herself, turning her carefully constructed investigation into a very different challenge.
Hannah Fry’s spreadsheet strategy
Earlier in the episode, viewers saw Hannah explain her approach to Joe Lycett. She revealed that she had been maintaining a detailed spreadsheet throughout her time in the castle, updating it every night to track the possible combinations of contestants who could be working together as Traitors.
Hannah had outlined the idea in a video published on her YouTube channel before the series began. Rather than trying to identify the Traitors through intuition alone, she planned to eliminate combinations that appeared unlikely or impossible, gradually reducing the number of potential groups.
The mathematician explained that the process involved considering every possible combination of three Traitors, then ruling out the groups that did not fit the evidence.
Her inspiration came from Alan Turing and his work on cracking the Enigma code during the Second World War.
Hannah explained that Turing’s approach involved starting with the available possibilities and systematically eliminating those that could not be correct until a workable answer emerged. She intended to apply the same principle to the castle’s mystery, using observations and evidence to reduce the field of suspects.
How the numbers could narrow down the suspects
Hannah’s calculations began with 21 contestants, giving her 1,330 possible combinations of three Traitors. She believed she could reduce that number significantly by making a few reasonable assumptions about how the game would unfold.
Initially, she intended to ask to be a Faithful and remain in that role. If she were not a Traitor, she could immediately rule out every possible combination that included her, reducing the total number of potential groups from 1,330 to 1,140.
She also considered the likelihood of host Claudia Winkleman selecting three people who shared an obvious characteristic. For example, Hannah thought it would be unlikely for all three Traitors to be comedians or for all of them to be young contestants.
By applying that assumption, she hoped to eliminate even more combinations.
The process would continue as the game progressed. Each murder and banishment would provide new information, allowing Hannah to remove additional possibilities from her spreadsheet.
Based on her calculations, she estimated that the number of possible Traitor groups could fall to just 72 by the fourth day. By day five, she expected to have only a handful of plausible combinations left.
With so few possibilities remaining, she believed she would be much closer to identifying the real Traitors.
Tracking seating arrangements and group behaviour
Hannah’s investigation extended beyond the identities of contestants who were eliminated. She was also paying close attention to where people sat and who spent time together.
She tracked the seating arrangements at breakfast and the roundtable, as well as the groups travelling together in cars. Her reasoning was that certain combinations of people would be less likely if three of them were secretly working together.
For instance, she considered it improbable that all three Traitors would travel in the same car or sit together in a row. While she accepted that two Traitors might share a car, she did not expect all three to do so.
A car carrying four contestants could therefore provide grounds to eliminate four possible combinations from her list, depending on who was travelling together.
Every interaction offered another potential clue, and Hannah intended to use these observations alongside the results of each round of the game.
Studying previous series for statistical patterns
Hannah had also done extensive preparation before entering the castle. She watched every episode of both the civilian and celebrity editions of the UK version of The Traitors, taking detailed notes on the behaviour of contestants playing as Traitors and Faithfuls.
She transferred her findings into a spreadsheet and analysed the data to look for statistically significant patterns in how Traitors behaved.
Her research uncovered several patterns she considered particularly valuable, although she did not reveal every detail of her findings in the episode.
Combining those observations with the changing list of possible Traitor combinations was central to her plan. Rather than relying on a single suspicious conversation or an individual’s demeanour, she wanted to build a picture from multiple pieces of evidence.
The approach was designed to become more effective as the number of contestants dwindled and new information emerged.
An unexpected recruitment changes everything
Hannah’s carefully prepared strategy took an unexpected turn during Thursday’s episode, when she was recruited by Maya Jama and James Acaster.
The recruitment followed the events surrounding the previous night’s game. At breakfast, both Hannah and Jerry Hall returned to the table unharmed, prompting suspicion and confusion among the remaining contestants because their return suggested that a recruitment had taken place.
Hannah had believed she was likely to be eliminated. Instead, she received a letter offering her the chance to join the Traitors, leaving her visibly shocked by the development.
Her recruitment changed the circumstances under which she had developed her mathematical model. The original plan depended on her remaining a Faithful, allowing her to eliminate every possible combination that included herself as a Traitor.
Now that she was secretly part of the opposing team, that assumption no longer held.
Rather than continuing to investigate the Traitors from the outside, Hannah must now conceal her own role while maintaining the appearance of a Faithful.
Her mathematical preparation may still inform how she approaches the game, but she faces a new challenge: using her analytical skills without revealing that she has become one of the people she originally intended to expose.