This chapel was to be known as the Chapel of St James, however, when a bust of St Thomas Aquinas arrived from Paris, it was decided to change the dedication of the chapel and place the bust there. The carved bust of St Thomas is in a niche in the reredos, flanked by mosaic panels representing theology and philosophy. On the frontal panel of the alabaster altar there is a mosaic of the host and chalice.

The inscription above the arch of the chapel reads: ‘Monuisti eum Paulo minus ab Angelis’ (Thou has made him little less than the angels).

The chair, lamp and kneeler here were used regularly by Archbishop Mannix for prayer and meditation.

The walls of the chapel are stencilled with motifs applicable to St Thomas Aquinas.