In 1840 Campbell conducted the prosecution against John Frost, one of the three Chartist leaders who attacked the town of Newport, all of whom were found guilty of high treason.
Kennington Common, now represented by Kennington Park, was the site of a gallows until the end of the 18th century, and was the meeting-place appointed for the great Chartist demonstration of the 10th of April 1848.
He took an active part in the Chartist agitation, but withdrew his support when the agitation for the repeal of the corn laws was removed from the Chartist programme.
On the r4th of June Mr Attwood, M.P. for Birmingham, presented to the House of Commons a Chartist petition alleged to have been signed by 1,280,000 people.
Meanwhile some monster Chartist demonstrations were being organized, and they commenced on the 4th of July with riots at Birmingham.