Colthurst’s family were large landed proprietors with estates at Ardrum, Ballyvourney, and Rathcoole, co. Cork and a long track record of service in the Irish parliament.
In June 1863 Colthurst was elected for the notoriously corrupt borough of Kinsale, partly on the strength of his donation of £1,000 for the construction of a public waterworks in the town.
In 1864, after serving on a select committee to consider a case of public compensation for a false conviction, Colthurst was drafted on to the important committee on the taxation of Ireland.
Though he regarded himself as ‘a steady supporter of the liberal party’, he pointedly abstained when Gladstone raised the Irish church question in April and May 1868. However, faced by yet another Liberal challenge at the 1868 general election, he claimed to ‘freely accept’ the Liberals’ position on the Irish church and was returned after pledging to support a Gladstone ministry.
Thereafter he voted for the disestablishment of the Irish church in 1869 but proved a stern critic of the 1870 land bill.
Colthurst was an active member of the Cork Agricultural Society, but although he was remembered as ‘a kind and indulgent landlord’, having spent more than his rental on relief works during the famine, his Blarney estate had been the scene of violent disturbances in 1849.
