Career
Dickson was elected to Westminster at the general election in 1874 as Member of Parliament for Dungannon in County Tyrone, and re-elected at the 1880 general election. His re-election was declared void on 10 June 1880 following a petition from the losing candidate, Colonel Knox. He was returned to Parliament the following year in a by-election for the County Tyrone constituency, and held that seat until the Tyrone constituency was divided at the 1885 general election.
He held that seat until the 1892 general election.