Thorney was of earlier date; coeval, indeed, with Peterborough. Of its foundation a graphic description is given by the chronicler. After telling how King Wulfhere of Mercia (whose wife was sister to St. Etheldreda), endowed Peterborough and its abbot Sexwulf with broad possessions, he continues:

"Then said the King: 'This gift is little, but it is my will they hold it so royally and so freely that neither geld nor fee be taken from it....And thus free will I make this Minster, that it be under Rome alone: and my will it is that all we who may not go to Rome visit St. Peter here.'

"While thus he spake, the Abbot prayed of him that he would give him whatsoever he should ask. And the King granted him. Then said the Abbot: 'Here have I God-fearing monks, who would fain live as anchorites (i.e., hermits), knew they but where. And here is an island which is called Ancarig[238] (Thorney). And my boon is that we might there build a Minster, to the glory of St. Mary, so that they who would lead the life of peace and rest may dwell therein.'

"Then the King answered and said: 'Beloved Sexwulf, lo! not only that which thou hast asked, but all else on our Lord's behalf I thus approve and grant.' ... And King Wulfhere first confirmed it by word, and after subscribed it with his fingers on the Cross of Christ" (i.e. he signed his name with a cross, on which he laid his finger, saying, "I deliver this as my act and deed," as we do with the seal on a deed at present. Seals did not come in till the Norman Conquest). Amongst the witnesses to his signature we find "Wilfrid the Priest, who was afterwards Bishop," i.e. the great St. Wilfrid of Ripon.

Thorney, however, was long in rising to abbatial dignity, and remained the abode of anchorites, so humble and so sequestered that in the great Danish raid of 870, when Ely and every other Religious House throughout the Fenland was destroyed, the plunderers did not take the trouble to seek it out, and it became a haven of refuge for the survivors of the sack of Crowland. The story is graphically told in the "Chronicle of Crowland"; in its present form probably a thirteenth century work, but obviously compiled from earlier sources.

After describing vividly the utter overthrow, at a great battle in Kesteven (West Lincolnshire), of the local forces hastily called out to meet the Danish host, he tells how a few poor fugitives got them to the Church of Crowland, and interrupted the Midnight Service with their crushing tidings.

"At this news all was confusion. And the Abbot, keeping with himself the oldest of the monks and a few of the children (of the Abbey School), bade all those in their prime to take along with them the sacred relics of the monastery (namely the holy body of St. Guthlac, his scourge, and his psalter) and the other chief treasures, and thus to flee into the neighbouring fens. With sorrow of heart did they his bidding, and, having laden a boat with the aforesaid relics and the charters of the Kings, they cast into the cloister well the frontal of the High Altar (which was covered with plates of gold) along with ten chalices ... and other vessels. But the end of the frontal, so long was it, always showed above the water; whereupon they drew it out and left it with the Abbot; for ever could they see the flames of the towns in Kesteven draw nigher and nigher, and feared lest the Heathen should on a sudden burst in upon them. So took they boat, and came unto the wood of Ancarig on the southern march of their islet. And here abode they with Brother Toretus, an anchorite, and other brethren, then dwelling there, four days, thirty in all, of whom ten were priests. But the Abbot, and two old men with him, hid the aforesaid frontal outside the church, to the North; and afterwards he and all the rest clad in their sacred vestments, met in Choir, and kept the Hours of Divine Service according to their Rule. And the whole of the Psalms of David went they through from end to end. After this sang they High Mass, the Abbot himself being Celebrant....

"Now, when the Mass was drawing to an end, and the Abbot and his deacon and subdeacon and the taper-bearers had already communicated in the Holy Mysteries, came the Heathen bursting into the church. And upon the very Altar, by the cruel hand of King Oscytel, was the venerable Abbot himself sacrificed, a true martyr and victim of Christ. All they who stood round and ministered with him were beheaded by the savages; and the aged men and children, as they fled from the Choir, were taken and questioned under the bitterest tortures, to make them show the treasures of the church. Dom[239] Asker, the Prior, was slain in the vestry, and Dom Lethwyn, Sub-prior, in the refectory. Behind him there followed close Brother Turgar, a ten year child, shapely, and of a fair countenance; who, when he saw his superior slain, besought earnestly that he too might be slain with him. But Earl Sidroc the Younger, touched with pity for the lad, stripped him of his cowl, and gave him a Danish cloak, bidding him follow everywhere his steps.... And thus, out of all who abode in the Monastery, old and young, he alone was saved; coming and going amongst the Danes throughout all his sojourn amongst them, even as one of themselves, through this Earl's favour and protection.

"Now when all the monks had been done to death by the torturers, and no whit of the Abbey treasures shown thereby, the Danes, with spades and ploughshares, brake open right and left all the sepulchres of the Saints round about that of St. Guthlac. On the right was that of St. Cissa, priest and anchorite, and of St. Bettelin, a man of God, erst an attendant on St. Guthlac, and of Dom Siward (the Abbot) of blessed memory. And on the left was that of St. Egbert, St. Guthlac's scribe and confessor, and of St. Tatwin, the pilot who guided St. Guthlac to Crowland.... All these did the savages burst open, looking to find treasure therein. And finding none, they were filled with indignation; and piling up all these holy bodies on a heap, in piteous wise, they set fire to them, and, on the third day after their coming, that is to say, on the 7th of the Kalends of October (September 25), they utterly consumed them, church and monastery and all.

"But on the fourth day off they went, with countless droves of beasts and pack-horses, to Medehampstead (Peterborough). And there, dashing at the outer precinct of the Monastery, with its barred gates, they assailed the walls on every side with arrows and machines. At the second assault the Heathen brake in, and, in the very breach, Tubba, the brother of Earl Hubba, fell grievously wounded by a stone cast. By the hands of his guards he was borne into the tent of Hubba his brother, and despaired even of life. Then did Hubba's rage boil over, and he was altogether wild against the monks, so that he slew with his own hand every soul clad in the religious habit; the rest sprang upon the rest; not one in the whole Monastery was saved; both the venerable Abbot Hedda, and all his monks, and all the lay-brethren were massacred; and Brother Turgar was warned by his master, Earl Sidroc, never anywhere to cross the path of Earl Hubba. Every altar was uprooted, every monument broken in pieces, the great library of holy books burnt, the plenteous store of monastic papers scattered to the winds; the precious relics of the holy virgins Kineburgh, Kinswith, and Tibba,[240] trodden under foot; the walls utterly overthrown; the buildings burnt up, church and all, blazing with a bright flame for five whole days after.