Just looked up what an inversion roll was, and that sounds like it. All the pain is on the outside of the foot.
Thanks for the advice, much appreciated. Yesterday the swelling was much greater around the outside of the foot, looked like a tennis ball was stuffed under there. Today there seems to be the same quantity of swelling, maybe a bit more, just spread all out over outside of the foot rather than concentrated on the impact point.
Yesterday I could hobble along leaning on a wall, today it is hopping to get anywhere. Currently waiting to get some crutches to make this manageable for the next few days. Hopefully the swelling will start going down over the next few days so I can walk again.