Between four and five in the morning, on 18 May 1843, spectators filled the galleries at the St Andrew's church in Edinburgh in order to witness the opening session of the annual General Assembly of the Church of Scotland. As the morning progressed, thousands more gathered outside the church; their presence confirmed the widespread expectation that this day would mark a decisive moment for the Scottish Church and society. By the time the commissioners to the General Assembly began taking their places shortly after noon, the pressure of the crowd had already become suffocating. At about half past two in the afternoon, the Royal Commissioner entered the church at the head of a procession of dignitaries, and the retiring Moderator, the Revd Dr David Welsh, Professor of Ecclesiastical History at the University of Edinburgh, led the Assembly in opening prayer. Then, at the point where it was customary to read out the roll of new commissioners, the Moderator rose and solemnly addressed the Assembly, amid a 'breathless silence'. 'There had been an infringement', he said, 'on the Constitution of the Church -- an infringement so great, that they could not constitute its General Assembly'. Instead, Welsh proceeded to read a long document, protesting against attacks made on the traditional liberties of the Scottish Church and nation by the civil authorities in the British parliamentary state -- attacks which touched on even the headship of Christ in his Church. As a result, it had become impossible for those who believed in the spiritual independence of the national Church to remain in the existing Establishment. He then laid the protest on the table, 'turned and bowed respectfully to the Royal Commissioner, left the chair, and proceeded along the aisle to the door of the Church'. He was followed in solemn procession by the Evangelical leaders of the Church, Thomas Chalmers, Robert Gordon, Patrick MacFarlan, and then by row after row of commissioners, until the left -- or Evangelical -- side of the church was nearly empty.

Outside, cheers rose from the crowd as the first of the outgoing commissioners came out of the church, but these were soon silenced as they were deemed unseemly for the occasion. There had been no plan to form a . . .