Born on 24 August 1913 at Ballybay, Co. Monaghan, he was the son of Robert H. Gallagher and the cousin of Ernest W. Gallagher. Deeply grounded in the social, political and religious life of Northern Ireland, he never served in the Republic of Ireland, which in those days was unusual for Methodist ministers. He was, however, a graduate of Trinity College, Dublin. He was arguably the leading churchman of his generation in Northern Ireland and gave distinguished leadership in church and society. No one showed greater concern to interpret and apply the gospel to Ireland's divided society, North and South, or possessed a stronger instinct for what was necessary and possible.
Hre was Superintendent of the Belfast Central Mission 1957-1979 and Secretary of the Irish Conference 1958-1967. In 1967 he was elected President of the Irish Methodist Church. A committed ecumenist, he was Chairman of the Irish Council of Churches 1967-1969 and Vice-President of the British Council of Churches 1979-1980. From the 1960s onwards he played a leading role in encouraging consultation and co-operation between the Protestant and Roman Catholic Churches in Ireland. He ws awarded an OBE and then a CBE in 1987 for distinguished service to community relations. He died in Belfast on 30 December 1999.