He knew, and had known for some time, who were the members of the so-called "Sealed Knot," i.e.that secret association of select Royalists resident in England who were in closest correspondence with Hyde and the other Councillors of Charles abroad, and were chiefly trusted by them for the management of the cause at home, Indeed, Sir Richard Willis, one of the chiefs of the "Sealed Knot," had for some time been in understanding with Cromwell, pledged to him by a peculiar compact, and revealing to him all that passed among the Royalists.

Hence, before the end of April, some of the members of the "Sealed Knot," and a number of leading Royalists besides, had been lodged in the Tower.

Among them were Colonel John Russell (brother of the Earl of Bedford), Colonel John White, Sir William Compton, Sir William Clayton, Sir Henry Slingsby (a prisoner in Hull since the Royalist rising of 1654-5, but negotiating there desperately of late to secure the officers and the town itself for Charles), Sir Humphrey Bennett, Mr.John Mordaunt (brother of the Earl of Peterborough), Dr.John Hewit (a London Episcopal clergyman), Mr.Thomas Woodcock, and a Henry Mallory.

It was part of the understanding with Willis that several of the prisoners, Willis's particular friends, should be ultimately released.

For trial were selected Slingsby, Clayton, Bennett, Mordaunt, Woodcock, Mallory, and Dr.Hewit.The trials were in Westminster Hall, in May and June, before a great High Court of Justice, consisting of all the judges, some of the great state officers, and a hundred and thirty commissioners besides, all in conformity with an Act of the late Parliament prescribing the mode of trial for such prime offences.