Unionists opposed Home Rule for several reasons:

The Irish Unionists, led by Sir Edward Carson, opposed home rule in the light of what they saw as an impending Roman Catholic-dominated Dublin government.

Some Unionists opposed secession, but afterwards either actively served and fought with the Confederate armies, or supported the Confederacy in other ways.

Unionists had also strongly opposed the proposal.

Unionists, almost all of them Protestants, oppose the agreement because it gives Ireland a consultative role in Northern Ireland's affairs.

As desired by the Nationalists, Asquith introduced legislation that would give Ireland Home Rule, but the Conservatives and Unionists opposed it.

The Unionists strongly opposed many of the proposed reforms of the new Liberal governments of Campbell-Bannerman and Asquith.

He faced no Independent Asquithian Liberal candidate and the Unionists did not oppose him, so he presumably received the Coalition coupon.

He was unable to contest the seat as there was no general election until 1918, when the Unionists did not oppose the sitting member, a coalition Liberal.

With Henderson's local support so high, the Unionists did not oppose him in the 1945 election.