I am currently working on a timeline where Macbeth King of Scots (1040-1057) survives and defeats Malcolm Canmore in 1057, and ends up surviving as king of scots and ends up having his son Macbeatha marry Ingerged daughter of Harald Hardrada in the early 1060s. When Harald invades England in 1066, Macbeth comes south, invading the northern part of England and helping contribute to defeating the armies of Morcar Earl of Northumbria and Harold Godwinson.
What I am wondering is would this alliance be enough to defeat William the Conqueror at Hastings, or in another battle?