In 1939 he entered St Mary's University College, Twickenham in London, but his studies were interrupted by the outbreak of World War II.

He received his episcopal consecration on the following 21 September from Archbishop William Godfrey, with Bishops James Donald Scanlan and Edward Wilson Douglas serving as co-consecrators, in St. Mary's Cathedral.

Pope Paul VI created him Cardinal-Priest of S. Chiara a Vigna Clara in the consistory of 28 April 1969, and therefore the first resident cardinal in Scotland since David Beaton, over four centuries earlier.

In 1978, he voiced strong opinions regarding the birth of Louise Brown, the first child to be successfully born from in vitro fertilisation, saying: "I have grave misgivings about the possible implications and consequences for the future.

He was a member of the Congregation for Divine Worship and the Discipline of the Sacraments and Pontifical Council for Social Communications, and once chaired the International Commission on English in the Liturgy.