The anthem for the service is Christus Factus Est by the Austrian composer Anton Bruckner (1824-1896).
Bruckner took the text for the piece from the New Testament – Philippians 2:8-9
Christus factus est pro nobis obediens usque ad mortem, mortem autem crucis. Propter quod et Deus exaltavit illum et dedit illi nomen, quod est super omne nomen.
English: King James Bible Version
Christ became obedient for our sakes unto death, even the death of the cross. Therefore God has highly exalted him and given him a name which is above every name.
The video is the Choir of Westminster Cathedral.