Great Britain south of the rivers Forth and Clyde, though the Isle of Man later had a Goidelic language, Manx. Northern Scotland mainly spoke Pritennic, which became Pictish, which may have been a Brythonic language. During the period of the Roman occupation of Southern Britain (AD 43 to c. 410), Common Brythonic borrowed a large stock of Latin words. Approximately 800 of these Latin loan-words have survived in the three modern Brythonic languages. Romano-British is the name for the Latinised form of the language used by Roman authors. British English is spoken in the present day across the island, and developed from the Old English brought to the island by Anglo-Saxon settlers from the mid 5th century. Some 1.5 million people speak Scots—which was indigenous language of Scotland and has become closer to English over centuries. An estimated 700,000 people speak Welsh, an official language in Wales. In parts of north west Scotland, Scottish Gaelic remains widely spoken. There are various regional dialects of English, and numerous languages spoken by some immigrant populations. Religion Christianity has been the largest religion by number of adherents since the Early Middle Ages: it was introduced under the ancient Romans, developing as Celtic Christianity. According to tradition, Christianity arrived in the 1st or 2nd century. The most popular form is Anglicanism (known as Episcopalism in Scotland). Dating from the 16th-century Reformation, it regards itself as both Catholic and Reformed. The Head of the Church is the monarch of the United Kingdom, as the Supreme Governor. It has the status of established church in England. There are just over 26 million adherents to Anglicanism in Britain today, although only around one million regularly attend services. The second largest Christian practice is the Latin Rite of the Roman Catholic Church, which traces its history to the 6th century with Augustine's mission and was the main religion for around a thousand years. There are over 5 million adherents today, 4.5 million in England and Wales and 750,000 in Scotland, although fewer than a million Catholics regularly attend mass. The Church of Scotland, a form of Protestantism with a Presbyterian system of ecclesiastical polity, is the third most numerous on the island with around 2.1 million members. Introduced in Scotland by clergyman John Knox, it has the status of national church in Scotland. The monarch of the United Kingdom is represented by a Lord High Commissioner. Methodism is