Lord Clarendon declares, that he believes this design, was to beget such a combination among the well affected parties, that they would refuse to conform to those ordinances of the twentieth part, and other taxes for the support of the war; and thereby or by joint petitioning for peace, and discountenancing the other who petitioned against it, to prevail with the Parliament to incline to a determination of the war, ’but that there ever was, says the earl, ’any formed design either of letting the King’s army into London, which was impossible to be effected, or raising an army there, and surprizing the Parliament, or any person of it, or of using any violence in, or upon the city, I could never yet see cause to believe.’  But it unluckily happened, that while this combination was on foot, Sir Nicholas Crisp procured a commission of array to be sent from Oxford to London, which was carried by the lady Aubigny, and delivered to a gentleman employed by Sir Nicholas to take it of her; and this being discovered at the same time Mr. Waller’s plot was, the two conspiracies were blended into one; tho’ the earl of Clarendon is satisfied that they were two distinct designs.  His lordship relates the discovery of Mr. Waller’s plot in this manner:  ’A servant of Mr. Tomkins, who had often cursorily overheard his master and Mr. Waller discourse of the subject which we are upon, placed himself behind the hangings, at a time when they were together; and there whilst either of them discovered the language and opinion of the company which they kept, overheard enough to make him believe, that his information and discovery could make him welcome to those whom he thought concerned, and so went to Mr. Pym, and acquainted him with all he had heard, or probably imagined.  The time when Mr. Pym was made acquainted with it, is not known; but the circumstance of publishing it was such as filled all men with apprehensions.’

’It was on Wednesday the 31st of May, their solemn fast day, when being all at their sermon in St. Margaret’s church, Westminster, according to their custom, a letter or message was brought privately to Mr. Pym; who thereupon with some of the most active members rose from their seats, and after a little whispering together, removed out of the church.  This could not but exceedingly affect those who stayed behind.  Immediately they sent guards to all the prisons, at Lambeth-house, Ely-house, and such places where malignants were in custody, with directions to search the prisoners, and some other places which they thought fit should be suspected.  After the sermon was ended, the houses met, and were only then told, that letters were intercepted going to the King and the court at Oxford, which expressed some notable conspiracy in hand, to deliver up the Parliament and the city into the hands of the Cavaliers; and that the time for the execution of it drew near.  Hereupon a committee was appointed to examine all persons they thought fit, and to apprehend some nominated at that time; and the same night this committee apprehended Mr. Waller and Mr. Tomkins, and the next day such as they suspected.’