Ælfric based his Life of St Edmund on Abbo of Fleury's Passio Sancti Eadmundi. Abbo wrote the Passio while he was visiting Ramsey between 985 and 987. Earlier, after his birth c. 940, Abbo had been an oblate at Fleury and was also educated in Orléans and Paris. He became Fleury's leading scholar of the second half of the tenth century, but sought refuge at Ramsey following an unsuccesful attempt to become abbot. He returned to Fleury in autumn 987 after he was appointed abbot. He was murdered in 1004 while on an expedition to reform a dependent priory at La Réole in Gascony. The manner of his death led the brothers of Fleury to consider him a saint, and one, Aimo, produced a vita.
Abbo's literary output was considerable (Sharpe 2001, §1) His writings covered computus, logic, grammar, canon law and biblical commentary and he produced an epitome of the Liber pontificalis. Alongside Gerbert of Aurillac, he was one of the first European scholars to know Boethius's treatises on logic. The Passio is his only known essay in hagiography.
It is curious that it was the monks of Ramsey that asked Abbo to write the Passio. After all, Edmund's cult centred on a rival monastery, Bury. However, Ramsey, founded in 966 at the instigation of Bishop Oswald of Worcester, had a particular interest in royal martyr cults, notably Æthelred & Æthelberht (the murdered grandsons of Eadbald, king of Kent (616-40)) and Edward the Martyr (d. 978), though his remains were held by Shaftesbury. The monks also claimed to have uncovered the relics of St Ivo, an alleged Persian archbishop, at nearby Slepe (now St Ives). Edmund himself was enthusiastically commemorated at Ramsey. The Historia Regum, the early sections of which were produced at Ramsey, mentions Edmund's death in 870 and notes that it would be fitting to include some thoughts on the honour of his passion (de cuius passionis honore libet aliqua inserere). There is also a couplet in his honour in the Metrical Calender of Ramsey:
Astra poli petit Eadmundus decoratus honore;
Gaudent Angligeni laudibus almificis
Edmund, deocrated with honour, makes for the heavens of the high;
The English people rejoice with generous praises.
Moreover, Abbo depicts Edmund as a saint worthy of veneration throughout East Anglia. Abbo dedicates his vita to Dunstan, archbishop of Canterbury, intending the text as memento of his stay at Ramsey (meae paruitatis apud Anglorum aecclesias non inutile monimentum). Lest they be lost to oblivion, Abbo records the narrative of events learnt by Dunstan from Edmund's armour-bearer and recited by Dunstan to Æthelstan. He begins with a description of the geography and history of the British Isles, particularly praising the fecundity of East Anglia. Edmund's birth and accession to the throne is treated briefly, along with his qualities as king, but it is the king's death that occupies the bulk of the text. The Viking invaders are minions of the devil, sent to tempt Edward into despair. Inguar demands that Edmund submit to him, but Edmund refuses and is put to death, dying 'like Christ before the governor Pilate' (quasi Christus ante Pilatum). The Danes hide Edmund's head, but once the Danes have departed, remembering the 'former benefits, and gentle nature of their king' (antiquam beneficiorum memoriam et ingenitam regis clementiam), the inhabitants of East Anglia search for the head. The head, protected by a wolf, calls for their attention, is found, reunited with the body and buried in a 'chapel of rude construction' (uili opere . . . basilica). Inspired by the frequent miracles wrought near this tomb, the citizens exhumed Edmund's body, intending to translate it to Bury-St-Edmunds, and found it incorrupt. Several miracles ensue at the new church, and Abbo closes with a meditation on Edmund's incorruption.
Abbo's passio was widely read throughout Europe and many manuscripts survive, though the four manuscripts associated with Anglo-Saxon England are most important for our purposes. These are:
London, Lambeth Palace Library, 362 - written, perhaps at Bury-St-Edmunds, perhaps before 1050)
Copenhagen, Kongelige Bibliotek, G. K. S. 1588 (4°) - written at Bury-St-Edmunds in the last quarter of the eleventh century
London, British Library, Cotton Tiberius B. ii - probably written at Bury at the turn of the twelfth century and includes Hermann's De miraculis S. Eadmundi
Paris, Bibliothèque Nationale, lat. 5362 - a collection of vitae of English saints, written at the turn of the twelfth ccentury either in England or in Normandy
As can be seen from this list, we have no manuscript early enough for Ælfric to have used and when production instensified, after 1050, it centred around Bury-St-Edmunds.
Further Reading: Abbo's Passio Sancti Eadmundi is printed by Winterbottom 1972 and translated by Hervey 1907.
The fullest treatment of the passio is Gransden 1995. The comments of Frantzen 2004 are also worth reading (pp. 51-72), as is Whitelock 1969..
On Abbo more generally see Mostert 1987.