Answer:
.It started because individual or group came from abroad and brought the Catholic Faith with him or them.Albanicus the Wise, a Celtic Historian, claims that the faith was here within a very short while after the death of Our Lord. [37AD.] The Archbishop of Tyre claims the first bishop of the British Church was Aristobulos, a brother of the Apostle Barnabus and a friend of Paul. {Acts.}