The Rt Rev Thomas McMahon, Bishop Emeritus of Brentwood and the longest-serving bishop in the diocese’s history, has died at the age of 89.
The diocese announced that “The Rt Rev Thomas McMahon, Bishop Emeritus of Brentwood Diocese, died peacefully at his home in Stock at 10 am on 24 November 2025. May he rest in peace.” Funeral details are expected to be released in due course.
Bishop McMahon’s life spanned almost the entire modern history of the diocese he later led. Born in Dorking in 1936 to Irish parents, he and his identical twin brother were educated at St Bede’s College, Manchester, after their father’s work required the family to move frequently. His parents later settled in Old Harlow, marking the beginning of his long association with Brentwood.
Accepted for priestly formation in 1954, he trained at Saint-Sulpice in Paris before being ordained at St John’s Seminary, Wonersh, in November 1959. His early ministry took him first to Colchester, then to Westcliff-on-Sea, where he served under Canon Thomas Bishop, the first priest ordained for the young diocese. In 1969 he was appointed parish priest of Stock, a post he would hold for an exceptional 56 years.
It was in Stock that many of the hallmarks of his later episcopal leadership first developed. He re-ordered the church, founded a parish council, and built strong ecumenical ties that drew him into diocesan and national work.
His interest in liturgy led to involvement in the Brentwood Liturgical Commission and the production of several publications, including The Mass Explained in 1977. Alongside parish duties, he served as Catholic chaplain to the University of Essex, offering Sunday Mass on the Colchester campus and ministering to students during the week.
When Bishop Patrick Casey resigned in 1979, McMahon was respected but not widely tipped to succeed him. His appointment was announced on 17 June 1980, his 44th birthday. Ordained bishop a month later by Cardinal Basil Hume, he made the unusual decision to continue living in Stock and to remain its parish priest, arguing that the location was more central to diocesan life.
Even as bishop, he continued to celebrate parish Masses, conduct funerals and weddings, and attend parish council meetings whenever commitments allowed.
Nationally, he became a familiar figure through his work in liturgy and church music, serving on the International Commission for English in the Liturgy and chairing several committees of the Bishops’ Conference. He cultivated close relationships with Anglican leaders in Essex and London and played a prominent role in local civic life, recognised by university honours and by his presidency of the Essex Show.
Within Brentwood, his tenure transformed the diocese’s physical and pastoral landscape. He oversaw major liturgical re-ordering projects, created new commissions and centres of formation and prayer, and established a twinning relationship with the Diocese of Dundee in South Africa. His most visible legacy remains the classical-style Brentwood Cathedral, dedicated in 1991, and the strengthening of its musical tradition through the Cathedral and Choral Trust and the expansion of the choir school.
Bishop McMahon celebrated his episcopal silver jubilee in 2005 and marked his ruby jubilee quietly during the pandemic. Having submitted his resignation in 2011, he continued to serve until 2014.
+ Requiescat in pace
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