What makes a Cathedral? Is it size, or antiquity, or location? None of these: a Cathedral is simply a church that contains a Cathedra - the throne of the Bishop. It is when the Bishop is seated at his throne, surrounded by his clergy and faithful people, that the Diocese is most truly realised, and his teaching is most famously and powerfully proclaimed when pronounced from the throne - ex Cathedra.
The Cathedra at Westminster Cathedral is modelled on the Pope's own throne at his Cathedral of St John Lateran in Rome. It was a gift to Cardinal Vaughan from the Hierarchy of England and Wales in 1900. The Cardinal's coat of arms appears on the back of the Cathedra.When the Cardinal uses the throne, cushions are supplied, or for major ocasions it is covered completely in silk.