In politics, most Presbyterians remained liberals for most of the 19th century. Probably the biggest political questions of the second half of that century were land ownership and Home Rule. Many Presbyterians were tenant farmers who resented the economic and political power of their landlords, most of whom belonged to the established church.

Presbyterian tenant farmers and their ministers were enthusiastic leaders and supporters of a campaign to achieve what became known as tenant rights, its aims summarised as the three Fs - fair rents, fixed tenure (no arbitrary evictions) and free sale of the tenant's interest in his holding. Landlord and government resistance aroused emotions and in the excitement of tenant-right meetings, wild words were spoken.

Such violent rhetoric, and the fact that Catholic priests and Presbyterian ministers were sharing tenant-right platforms, alarmed establishment Protestants like Henry Cooke, who accused the tenant-right movement of communism and warned of the folly of repeating the disaster of 1798. The Presbyterian General Assembly, however, gave the movement its countenance.

The union of Presbyterian and Catholic in the tenant-right movement was endangered, however, by sectarian feeling when the British government responded to the reintroduction of a Catholic hierarchy in Britain - hitherto a missionary province governed by Vicars Apostolic - by passing an Ecclesiastical Titles Bill. It forbade Catholic bishops from taking the titles of existing Anglican bishoprics.

Catholics, particularly in Ireland, interpreted this as a new form of penal legislation and a Catholic Defence Association was formed in Dublin in which Catholic tenant-right leaders were involved. The tenant-right movement survived these stresses, however, and its aims were achieved through government legislation, beginning with Gladstone's Land Act of 1870. Before that Act was on the statute book, Gladstone had disestablished the Church of Ireland (in 1869), the landlords' church. There had long been a question mark over the Church of Ireland, as the church of a minority, being the national church.

Few Presbyterians followed Henry Cooke in his opposition to disestablishment and most Irish Presbyterians supported Gladstone's reforming agenda in Ireland. However, they were horrified by his "conversion" to Home Rule. As a liberal, Gladstone believed every nation had a right to self-government and that the least Britain could offer Ireland was home rule within the British state. Most Irish Protestants, however, believed an Irish parliament would mean Catholic domination; that "Home Rule would be Rome Rule". Presbyterians, in particular, having suffered under a Protestant ascendancy, were determined not to submit themselves to a Catholic ascendancy.

The General Assembly agreed unanimously that "a separate parliament for Ireland would, in our judgment, lead to the ascendancy of one class and creed in matters pertaining to religion, education, and civil administration. We do not believe that any guarantees, moral or material, could be devised which would safeguard the rights and privileges of minorities scattered throughout Ireland against encroachment of a majority vested with legislative and executive functions."

Gladstone found it hard to understand that the Ulster Presbyterians who had led the United Irish movement a century before were implacable opponents of his Home Rule policy.

The nub of the Irish Presbyterian opposition to Home Rule was their lack of trust in an Irish Catholic government to maintain civil and religious liberty for Protestants in Ireland.

By 1886, most Irish Presbyterians had abandoned one of the objects of their United Irish ancestors, what William Drennan had defined as "a total separation from Britain". Their 19th-century experience had bound them economically, politically and spiritually to Britain. The increasing identification of Irish Protestantism and unionism paralleled, and was in part a consequence of, the identification of Irish nationalism and the movement for Home Rule with the aspirations of Catholic Ireland.

Shaw, like most of their spokesmen, insisted that they were Irish and loved Ireland, although they believed the interests of all the people of Ireland were best secured by the union. They saw no contradiction in being both Irish and British.

Irish Presbyterian opponents of Home Rule resented allegations that they had all become Orangemen and Tories. The Rev "Roaring Hugh" Hanna, a vigorous and outspoken opponent of Home Rule and an Orangeman, declared that he knew of only three Orangemen among the ministers of the General Assembly.

A Liberal Unionist Association was formed by men like Thomas Sinclair, but as the Home Rule struggle intensified there was considerable pressure on opponents of Home Rule to unite under the umbrella of what became the Ulster Unionist Party. The fact that the British Tory party espoused the unionist cause made it difficult for unionists to resist being drawn into the Tory camp.

The Rev Dr Finlay Holmes is a former Moderator of the Presbyterian Church in Ireland and taught church history at Magee College in Derry, Union Theological College and the Faculty of Theology in Queen's University, Belfast. His book The Presbyterian Church in Ireland: A Popular History (£7.99) has just been published by Columba Press.