Aristobulus, one of the Seventy apostles and disciples appointed by the Lord Jesus, is said, by St Hippolytus (d.235) who was a bishop in Italy,martyr and author of several writings, to have been the first bishop of Britain.
There have been several instances where churches have wished to trace their foundation to an early time and provided the name of some person as the source of their status and authority even when, historically, this is unlikely and unsupported. This makes for some uncertainty in this matter.
The liturgical tradition provides an Icon and Troparion.
Troparion in tone 5
O Holy Apostle Aristobulus, first Bishop of Britain,
intercede with the merciful God
that He grant unto our souls forgiveness of sins.