When I went to School in the 1940s I was taught that the Church came to Britain in and about 37AD, in the reign of Tiberius. Later we were taught that the Roman ,"Ecumenical’, or Latin, Councils of the Middle Ages gave precedence to the British Church on account of its antiquity, arriving in Britain about 40AD.
The Bishop of Tyre, Dorotheus, (300AD.) said that Simon Zelotes “was at last crucified, slain and buried in Britain.” (Synopsis de Apostol

Hippolytus (160AD) mentions Aristobulous as, Bishop of the Britains.) Again, Dorotheus mentions him as Bishop of the Britons. Whilst Ado Archbishop of Venice tells us that Aristobulous was martyred here. Catholic Messenger no 289, in an article written by a Romanist Scholar states quite plainly that at least one “English,” (sic) Bishop was at Nicea.
By the time of Augustine Christianity had been in this country for over 500yrs.
British Churchmanship is of very great antiquity. It might have its troubles today, but it is of the Body!