It must always be borne in mind that the conversion of the inhabitants of Britain from Paganism to Christianity was a very gradual process, extending over a period of two hundred years at least. It seems probable that during the last hundred years or so of the Roman occupation of Britain the Christian faith may have been accepted by a limited number of the native population; but almost as soon as the new religion began to take root in England it was entirely swept away by the Saxon conquest, and the few converts who were not exterminated by the ruthless Pagan invaders fled for refuge to Wales and Cornwall. The archæological evidence of the existence of Romano-British Christianity is extremely scanty. Out of the hundreds and hundreds of inscribed and sculptured monuments belonging to the period of the Roman occupation of Britain there is not one which bears a Christian symbol or shows a trace of Christian art. There are only two instances of the occurrence of a Christian symbol on a Romano-British structure, namely, (1) at Chedworth,[349] where the Chi-Rho Monogram is carved twice upon a stone in the foundation of the steps leading into the corridor of a Roman villa there; and (2) at Frampton,[350] Dorsetshire, where the same Monogram forms part of the decoration of a mosaic pavement in one of the rooms of a Roman villa. As Romano-British Christianity produced no effect on the art of this country, we are not further concerned with it. [349] _Journ. Brit. Archæol. Assoc._, vol. xxiii., p. 228. [350] S. Lysons’ _Reliquiæ Brittanico Romanæ_, No. 3, pl. 5. Whilst England remained under the dominion of Saxon Pagandom for a century and a half in some parts, and for nearly two centuries in others, Christianity spread rapidly from Gaul to Cornwall, Wales, and the south-west of Scotland, and thence to Ireland. After the Saxons were converted by St. Augustine, in A.D. 597, there was a return wave of Celtic Christianity from Ireland to Iona, and from Iona to Lindisfarne, in Northumbria, which was founded A.D. 635. The localities where Christianity was first planted in Britain are indicated archæologically by the geographical distribution of monuments bearing the Chi-Rho Monogram, which is as follows:— CORNWALL. St. Just. St. Helen’s Chapel. Phillack. Southill. CARNARVONSHIRE. Penmachno. WIGTOWNSHIRE. Kirkmadrine. Whithorn. As the Chi-Rho Monogram does not occur on the early inscribed stones of Ireland, but in place of it the cross with equal arms expanded at the ends, enclosed in a circle, which is derived from the Monogram,[351] it naturally follows that Irish Christianity is later than that of Cornwall, Wales, and the south-west of Scotland. [351] See J. R. Allen’s _Christian Symbolism_, p. 94. The Chi-Rho Monogram occurs on inscribed monuments in Gaul between A.D. 377 and 493.