Context:

A biography of Mary Queen of Scots by John Guy is extensively quoted throughout the episode. While the specific title is not mentioned, the hosts repeatedly cite Guy's work with phrases like 'John Guy puts it really well,' 'to quote John Guy,' and reference 'reading John Guy's kind of comprehensive takedown of the casket letters.' This appears to be a major scholarly biography used as a source for the episode.

Context:

Referenced twice - first when describing Morton as 'the most villainous of the Scottish lords,' and again when describing the murder of Rizzio. John Guy is a historian known for his biography of Mary Queen of Scots, which is likely the source being referenced.

Context:

Referenced as 'his biography' of Mary Queen of Scots. Quoted regarding Darnley's character being 'tainted by recklessness, sexual excess, pride and stupidity' and other aspects of Mary's reign.

Context:

Tom holds up and describes 'this titanic definitive biography of Mary by John Guy, which came out about 20 years ago' - noting it has been retitled for the 2018 film and features Saoirse Ronan and Margot Robbie on the cover with the subtitle 'Two Queens, One Future.'

Context:

Explicitly identified as a biography of Mary published in 2004 that 'was the inspiration for the Saoirse Ronan film.' Described as providing 'a solution to the crime' of Darnley's murder through careful examination of original documents, particularly English reports to Cecil that had been miscatalogued in Victorian times. The hosts note they 'will be drawing very heavily on Guy's work' for their account.