On 14 May 1681 Cornish, with other members of the corporation, went to Windsor to present a petition to the king for the summoning of parliament, but Charles declined to receive the deputation.

John Rumsey, arrested on suspicion of complicity in the alleged Rye House plot in 1683, was aware of Cornish's unpopularity with the authorities, and offered to produce evidence implicating the alderman in the conspiracy.

But Cornish was narrowly watched by the agents of the court, and since he proved himself no more conciliatory to James II than to his brother, it was deemed advisable in 1685 to remove him.

Goodenough, an attorney whom Cornish had antagonised by declining to make him his deputy-sheriff in 1680, arranged with Rumsey to corroborate the false testimony with regard to the Rye House plot, and to add evidence proving an attachment for the Duke of Monmouth.

The indignation which he displayed in his speech from the scaffold led enemies to state that he died drunk, but William Penn, who witnessed the execution, declared that Cornish showed the resentment of an outraged man.

Remarks on the Tryal of Henry Cornish, an attack on the judicial procedure at the trial, was written by Sir John Hawles, solicitor-general under William III.