http://en.wikipedia.org/wiki/Alfred_the_Great

,,[...]the Viking army did withdraw from Reading in the autumn of 871 to take up winter quarters in Mercian London.''



http://www.historyonthenet.com/Chronology/timelinealfred.htm

,,886 	
Alfred takes London 	
Alfred the Great captured London, allegedly after defeating a Danish garrison. However, as London was in the Kingdom of Mercia, Alfred, turned London over to Mercian control.''



http://users.idworld.net/rrichard/militar3.htm

,,872 Ivarr dies of natural causes in Dublin. Harald I gains control of Norway. [More] Danes pull back from Wessex and invade Mercia, occupying London. [More]''


http://books.google.pl/books?id=QnDtohOe8-QC&printsec=frontcover#v=onepage&q&f=false (nie mam cierpliwości do googlebooks na GPRSie, ale może coś jest ;) )