Dillon was from humble origins in Wales, and worked for years as a farm labourer, bullock driver and carrier before acquiring land. He was a rarity amongst Liberals as a runholder with about 3,500 acres (14 km2). A poor speaker and sneered at by William Russell as illiterate, he appealed as a "man of the people" who had made his way by his own efforts.
He retained the image of the rugged pioneer.
Short, barrel-chested, bushy-bearded and usually clad in thick country tweeds. He was 64 when he entered Parliament and was known affectionately as "Dad" by other members.