Michael Bernard Gaine was born in London on 21 July 1930, the son of Daniel and Bridget Gaine. He was educated at Seafield Convent, followed by St Mary’s College, Crosby and St Joseph's College, Upholland where he was ordained priest in the college chapel on 12 June 1954 by Archbishop William Godfrey. Following ordination, he was appointed junior private secretary to the Archbishop.
In 1957 he was appointed assistant priest at St Mary's, Woolton and also read for a BA degree in social science at Liverpool University. From 1961–62 he trained as a teacher at St Mary's College, Twickenham before taking up a teaching post at Gunnersbury Catholic Grammar School in London. In 1964 he returned to the Archdiocese, teaching at St Kevin's School, Kirkby while living at Upholland College. The following year he was appointed to the staff of Christ's College, Liverpool and within a short time set up the Liverpool Institute for Socio-Religious Studies, which published pamphlets on social issues and gave advice to religious congregations. He continued his teaching until 1989, in what had by then become Christ's and Notre Dame College, by which time he was head of the social science department.
His talents and energies were also harnessed beyond the Archdiocese. For a number of years he served on the social welfare commission of the Bishops' Conference and was also a trustee of Tantur Ecumenical Institute in Jerusalem. However, many associate him particularly with his work as a founder member of the Movement for the Ordination of Married Men.
In August 1989 he returned to parish life for his sole appointment as parish priest at St Mary's, Highfield Street. As well as attending to the regular demands of parish life, he also regularly celebrated Latin Mass in the extraordinary form on Sunday afternoons and maintained a warm and close relationship with Liverpool Parish Church. He remained at Highfield Street until just after his 70th birthday in 2000, at which time he retired to West Kirby. From 2011 increasing frailty necessitated Michael being cared for in a number of different care homes, before he finally settled at James Nugent Court in Liverpool.
His Funeral Mass was celebrated by Bishop Tom Williams at St Charles' Church, Aigburth on Monday 9 October prior to burial at West Kirby.