In July 1627 Coryton was arrested for refusing to subscribe the forced loan of that year, and imprisoned in the Fleet Prison, where he remained until March 1628.
After his fellow MP Sir John Eliot had read a remonstrance on tonnage and poundage, the Speaker had refused to put it to the house, and had risen to dissolve the assembly.
Finch was then held in his seat by Denzil Holles and Benjamin Valentine while resolutions against Arminianism and illegal exactions were read and declared carried.
Coryton was subsequently charged with having aided and abetted Eliot, Holles, and the rest, and even with having assaulted Francis Winterton, member for Dunwich, Suffolk.
His administration of justice in the Stannary Courts gave much dissatisfaction to suitors, and in or about 1637 he was arrested on a charge of false imprisonment.
[4] He was at the time Mayor of Bossiney and was found guilty on petition of falsifying the returns for the election at the Parliamentary constituency of the same name.