Someone pointed out to me that accessing my demo from their Chrome worked fine and, when I tried it, it did too. So it had to be my DEV box. I decided to leave the question up as it may help others but the answer was a simple reboot :-(
As this is my development machine I was going to localhost so, not sure if that affected things but, I simply couldn't clear out something Chrome was seeing from earlier tests.
As mentioned, I tried: -
Anyway, all's well that ends.