Thanks for your reply.
Read a book some years ago that noted the dryer-than-usual September weather in southern England in the weeks leading up to the Battle of Hastings. The author felt that the firm, dry ground would have favored the Norman calvary in their ability to gather speed charging uphill toward the Saxon shield wall and allowed sustained attacks over ground that, in a more typically wet fall, would have been churned into a man and horse-immobilizing morass. In such an event, the stirrup would have counted for little. (When thinking of the muddy battlefield alternative, I conger up images of the Kenneth Branagh depiction of Agincourt: rain, mud, clanging steel, and blood.)
IIRC, the battle lasted far longer than normal for those times; a testament to the stubborn courage of the House Carls, depleted as their ranks were, and all the more admirable after the death of King Harold sealed their fate.
The Normans were ethnically a little of both, speaking French with a lot of loanwords. The same thing happened after the Conquest — they picked up and dropped off words from and into English, like ‘beef’ and ‘mutton’.
And SL, Britain is indeed one of the most invaded places on Earth, although there hasn’t been a successful one since the William and Mary’s “Glorious Revolution”. The old Celtic work “The Book of Invasions” more or less documents the pre-Roman invasions of the British Isles, and there’s a lot of time between the melting of the glaciers and the beginning of the surviving folk tradition for many others.