In 1242 William de Marisco and his associates were famously executed for plotting to murder King Henry III. The chronicle of Matthew Paris illustrates William being drawn by horses to the gibbet for execution. He and his companions were not the first, however, to have been tried for planning to murder Henry. In 1225 three knights were accused of doing just that. Few historians have noted this case, and those who have done so have dismissed it lightly, primarily because the accuser was not believed and the three knights were acquitted. The indications, however, are that the regime actually took the accusation very seriously and that the trial was a thorough one. Consequently the record of the trial has much to tell us about political practice and about the beliefs, values and expectations that underpinned them, that is to say about the political culture of early thirteenth-century England. Moreover, it allows us to observe the interaction between that political culture and what actually transpired within and, to some extent, beyond the court.

The case is recorded in three separate rolls. The fullest, KB 26/88, forms the basis of the transcription in the published Curia Regis Rolls. The process notes in the margin suggest very strongly that this was the roll made for Martin de Pattishall as the senior judge. Unfortunately, the membrane which contains the case is severely rubbed down the right-hand side making some of it illegible. Some of the wording can be supplied from the other two rolls. KB 26/88 contains additional details, including the verdict, which are absent from those.

What the record says is as follows: Richard Fitz Nigel appeals Ralf de Bray, William Fitz Ellis and Vitalis Engaine that the three of them had arranged for the death of the lord king by poisoning him. Richard says that they arranged this in Westminster Hall, and that he overheard them. Moreover, he heard Ralf and Vitalis arrange this a second time in Vitalis's manor house outside St Neots. They asked him to be an accomplice, and offered him land if he would agree to it. And that they did this ‘wickedly and in felony’ he offers to prove against them by his body (that is to say, by battle), as the court decides.