One Matthew Smith, nephew to sir William Perkins, had been entertained as a spy by this nobleman, who finding his intelligence of very little use or importance, dismissed him as a troublesome dependent.

Then he had recourse to the earl of Monmouth, into whom he infused unfavourable sentiments of the duke, insinuating that he had made great discoveries which from sinister motives were suppressed.

Monmouth communicated those impressions to the earl of Portland, who enlisted Smith as one of his intelligencers.
Copies of the letters he had sent to the duke of Shrewsbury were delivered to secretary Trumball sealed up for the perusal of his majesty at his return from Flanders.

When Fenwick mentioned the duke of Shrewsbury in his discoveries, the earl of Monmouth resolved to seize the opportunity of ruining that nobleman.

He, by the channel of the duchess of Norfolk, exhorted lady Fenwick to prevail upon her husband to persist in his accusation, and even dictated a paper of directions.
Fenwick rejected the proposal with disdain, as a scandalous contrivance; and Monmouth was so incensed at his refusal that when the bill of attainder appeared in the house of lords, he spoke in favour of it with peculiar vehemence.