Brooke would retire, rather surprisingly, on health grounds in 1963. Sinclair thought he would face some sort of challenge but this did not arrive. The party paved the road for him as he took up the office of Prime Minister with grace at the tender age of 67, the oldest PM Ulster had yet. He immediately set to work continuing what he had done as Finance Minister, appointing Education Minister Terence O'Neill to succeed him. He would set up Five Economic Zones across Northern Ireland to modernise industry and created a new city in Armagh, linking Portadown and and Lurgan, naming it "Blackwater," after a nearby river. His decision not to name it after the late James Craig rankled with some unionists, as did the placement of a new university in Derry rather than Coleraine. Sinclair utilised his stellar record as Finance Minister and popularity with the public to put down internal dissent. In addition, Sinclair's economic record as PM seemed to be rather strong, having brought both Ford Automobiles and Goodyear to Ulster. This, along with co-operation with the Northern Ireland branch of the Irish Trades Union Congress, helped bring unemployment down. Sinclair of course faced some attacks for being a big spender but these would subside as results began to show themselves.
Regarding the Irish matter, Sinclair would further anger hardliners within his party by arranging a meeting with Taoiseach Sean Lamass in 1965, as well as signing an agreement regarding electricity supplies. This would tie in with both his economic revolution and his attempt to boost Northern Ireland's image. As for the latter, Sinclair would do things like visit Catholic bishops and made an effort of improving standards of funding for things like Catholic schools. Anger began to grow at Sinclair despite the clear success his policies were having, and this culminated in the Reverend Ian Paisley setting up his "Sinclair Out" campaign in opposition to the softening of unionist rhetoric coming from the Prime Minister. Sinclair was considered a strong leader, but there was only so much respect he could command. The 1965 General Election shored up his support, producing a massive landslide in favour of the UUP and decimating the voteshare of the moribund Nationalist Party.
Some relative peace and stability would be broken up by the rise of discontent among the minority nationalist population. Sinclair was a marked improvement over the bitter old man Brooke, who once famously boasted about never hiring a Catholic in his life, but the structural injustices of Northern Ireland remained, such as the clear favouring of Protestants when it came to allocation of housing and the property requirement to cast votes. Unrest appeared to grow as the Northern Ireland Civil Rights Association was formed in 1967. Furthermore, the election of Gerry Fitt to Westminster lead to a greater presence for Northern Ireland there, and as such more attention was paid towards the state of civil rights in the province. Naturally, unionist hardliners pressed against action being taken and supported suppressing the marches, with William Craig being allowed to place a ban on them marching while negotiations took place. NICRA had demands to end what they viewed as unjust laws, and Sinclair would have to face this at some point or risk severe repercussions as violence seemed to flare up. Their first march from Coalisland to Dungannon was a success and was relatively tepid, but a march held in Derry became infamous for the "disgusting" police response, which was recorded on RTE cameras and nearly prompted a response by the new Taoiseach Jack Lynch, which he put off after private assurances by Sinclair, who put forward a reform plan that NICRA members would as a whole consider acceptable. The movement towards One Man One Vote was there, as was the establishment of an ombudsman to look at discrimination, plus measures to deal with housing and allocation of government jobs. These reforms were gradual, to be introduced over a period of two years, to the grumbling of many. Yet, it did something to dilute tensions in spite of rage within the party. Also, Home Affairs minister Craig would be fired due to his growing appearance as a figure of hate by those in the civil rights movement. Against many of the odds, Sinclair put off government action as Prime Minister Harold Wilson and Home Secretary Jim Callaghan seemed to be more than welcoming of his efforts, though informed him of a possible need to deploy the army if tensions unraveled again. This was considered further and eventually done as a peacekeeping measure in late 1969 after consultation between Stormont and Westminster.
By the time he had almost been finished Sinclair was in his mid 70's and had not the energy to continue on anymore, and so he announced his resignation as Prime Minister, Unionist leader, and MP for Belfast Cromac in early 1970. The leadership race to succeed him was a contest between his preferred successor Jack Andrews and the former Home Affairs minister William Craig, with Andrews pulling out a victory. Andrews would go on to win another landslide victory in 1970, however with a growing number of conservative unionists that were either in the UUP or joining Ian Paisley's Protestant Unionist Party. He would eventually be granted a peerage by the government of Ian Gilmour, and would serve out the rest of his life in relative comfort, well regarded as a reformer. He cropped up as a possible candidate to lead a National Unity government during the turbulence of the early 70's, but this never manifested to much.
Brian Faulkner was an interesting man, in a way, and in a sense robbed himself of a successful career. He was the youngest MP elected to the Northern Irish Parliament in 1948, and was mooted for greater career success, but after some consideration, decided to stand in the 1953 North Down by-election to replace Walter Smiles, who died in the capsizing of the Belfast Victoria. He was elected without any opposition and would attempt to make a name for himself at Westminster, to little avail. He contested the leadership of the Ulster Unionist Party in 1970 and 1981, failing in both attempts as the party preferred to choose members from the Stormont Parliament rather than the Westminster Parliament. His conservative views became clear but as the party's Chief Whip during the 70's and 80's he pushed through policies that were not to his liking. He received a knighthood in 1985, partly rumoured due to his decision to help prop the Shore government up in 1981 when it looked about to collapse. He died in 1994, a few years short of becoming Father of the House, and the by-election to replace him was won by the liberal unionist Brian Wilson on a much reduced majority.