sentences:  The Ulster Unionists and Democratic Unionists made an electoral pact and on 23 January 1986, staged an ad-hoc referendum by resigning their seats and contesting the subsequent by-elections, losing only one, to the nationalist Social Democratic and Labour Party (SDLP).However, unlike the Sunningdale Agreement of 1974, they found they could not bring the agreement down by a general strike.This was another effect of the changed balance of power in industrial relations.