In around 880, King Alfred the Great agreed the following treaty with Guthrum (d. 890), one of the viking leaders. The text begins: ‘This is the peace which King Alfred and King Guthrum and the councillors of all the English people, and all the people who are in East Anglia, have all agreed and confirmed with oaths. First concerning our boundaries: up the Thames, and then up the Lea, and along the Lea to its source, then in a straight line to Bedford, then up the Ouse to Watling Street’.

This treaty is important for revealing the extent of Alfred’s enlarged kingdom, comprising Wessex and parts of the former kingdom of the Mercians. London, in particular, remained on the ‘English’ side. The text also suggests that Scandinavian settlement was already taking place in East Anglia. Before the treaty was agreed, Guthrum had left his base at Cirencester and taken his army back to East Anglia, where they settled and ‘shared out the land’. Much may lie hidden beneath the bare record of these events.

The treaty is preserved in a book compiled around 1100, which contains an important collection of legislation from the time of Alfred to that of Cnut.