Simon de Montfort led the barons' rebellion against Henry III in 1265, and was killed at the battle of Evesham. The rebellion had attempted to force changes in central and local government on the king, and was to some degree a popular protest movement. Earl Simon was immediately the object of an unofficial miracle cult, which lasted until c.1280. In England no other layman had attracted a miracle cult since Earl Waltheof (d.1076). It centred on Montfort's grave in Evesham abbey, and it had to be practised in secret for at least two years. Earl Simon was never officially canonized. The Evesham miracle book records some two hundred alleged events, and the contemporary laments, prayers, and hymns reflect the bitterness, despair and longing that animated the cult.

The only previous edition of the miracle book appeared in 1840; most of the verses and prayers also appeared in print long ago, but in scattered publications and to no uniform standard. The documents are mostly in Latin, with a few in French. Only some of the items have hitherto been translated into English prose. Collectively, the documents illustrate local and social history, popular religion, and contemporary opinion across a range of social ranks at a time of crisis.