In 1773, he declined an offer from Lord North of a post in Bengal to supervise and regulate the activities of the East India Company.

"[6] Encouraged by this difference in view, an annual pension of £500 (equivalent to £80,000 in 2023),[7] and a seat on the Treasury Board, he crossed the floor to become part of the Government in 1774.

Consequently, when the new parliament sat in 1780 the government was determined to replace him, citing grounds of his ill health over the vocal objections of Norton himself.

[2] When in the chair, Cornwall would alleviate the tedium of long debates by drinking draughts of porter that were brought to him from Bellamy's - a refreshment house in Old Palace Yard.

According to Nathaniel Wraxall, "Cornwall possessed every physical quality requisite to ornament the place - a sonorous voice, a manly as well as an imposing figure, and a commanding deportment;"[16] though he went on to criticise his drinking.

According to the Oxford Dictionary of National Biography "though he never achieved distinction as speaker, his frequent and well-informed interventions from the chair demonstrated initiative and judgement.

He called MPs to account for unparliamentary behaviour and ruled on procedural matters, such as allowing the innovation of parliamentary questions in May 1783.

On 2 January 1789 the Commons Journal records that "the Clerk at the Table acquainted the House that we was extremely sorry to inform them that Mr Speaker died this morning.

"[13] An autopsy was carried out where "a large quantity of cold water was found in his stomach; and one of his collar bones turning with a sharp point to his lungs, had formed an abscess and occasioned his death.