5th of December was the traditional date for celebrating the feast of St Birinus, Bishop of Dorchester, as given in the Missal with the mass of common of bishops. The chapter always celebrated its feast of title with a Solemn High Mass on or near to 5th December, usually at St Barnabas' Church in Jericho.
With the revision of the Church of England calendar the day given to St Birinus is now 4th September and the propers for mass are now those of missionaries.
