Today is the feast of St. Gildas the Wise,  the earliest British historian. His writings were an important source for Bede and Alcuin.
Gildas was born in Scotland, on the banks of the Clyde, and he died at a monastery he founded in Brittany. His dates are in question by modern scholars; he was probably born before 500 and probably died after 550. He spent much of his religious and priestly life in Wales and Ireland before retiring to Brittany. The most famous of his surviving works is De Excidio Britanniae,  (The Ruin of Britain).
He describes the "island of Britain":
"Its plains are spacious, its hills are pleasantly situated, adapted for superior tillage, and its mountains are admirably calculated for the alternate pasturage of cattle, where flowers of various colours, trodden by the feet of man, give it the appearance of a lovely picture. It is decked, like a man's chosen bride, with divers jewels, with lucid fountains and abundant brooks wandering over the snow white sands; with transparent rivers, flowing in gentle murmurs, and offering a sweet pledge of slumber to those who recline upon their banks, whilst it is irrigated by abundant lakes, which pour forth cool torrents of refreshing water."
He berates the kings and the priests and the people for being "impotent" when oppressed by enemies -- the Romans, the Scots (Irish Dál Riata), the Picts, and, worst of all, the "impious Saxons, a race hateful both to God and men".
A map of Britain, in the time of Gildas. 
Michael E. Jones, in The End of Roman Britain,  Cornell University Press, 1996, suggests that Gildas's vocabulary (including naval terms), diction, and grammar indicate that the date of De Excidio should be pushed back. St. Gildas may have written his jeremiad at the beginning of the sixth century rather than in the middle.
Peter Salway, in A History of Roman Britain, Oxford University Press, 1993, demonstrates how scholars and archaeologists evaluate Gildas's claims of an Anglo-Saxon take-over in the 440s.
There are a number of bell stories told about Gildas. In one, he is said to have sent a bell to Brigit in Ireland that he had cast himself, a gift charged with significance in a culture where a bell was an emblem of godhead. Ollaves, the master poets of Ireland, second only to kings in the number of colors they were allowed to wear and where they sat at table, carried golden branches with tinkling bells in honor of Brigit, Triple Goddess of poetry, healing, and blacksmithing.
Even after Christianity came to Ireland, and Brigit became St. Bridget, bells continued to be extremely important. The Catholic Encyclopedia's article on Bells  makes that plain. Scroll down to the fourth paragraph to see what bells meant in the Ireland of St. Gildas's time: "The evidence for the extraordinary veneration with which these bells were regarded in Celtic lands is overwhelming." A fitting tribute to Brigit the Exalted from Gildas the Wise.