This was organised by the Newman Society, a Catholic student society of the University. The feast was the Martyrs of Oxford University, a feast specific to the Archdiocese of Birmingham in the calendar proper to the 1962 Missal, which falls on 1st December.
The celebrant was Fr Daniel Lloyd, Parish Priest of Holy Rood in the Abingdon Road, just over the river from the Chaplaincy. Thanks are due to the Catholic Chaplain, Fr Matthew Power SJ. To my knowledge this is the third public Traditional Mass celebrated in this chapel; they have previously taken place in 2013 and 2018. [Update: I'm told Mgr Alfred Gilby celebrated Mass there before a Newman Society dinner in 1995 or 1996.]
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