Thank you, I'll try again tonight. It was so straightforward when I did it on the course I just seem to end up with rubber and fingers everywhere and no idea whether the tube is twisted inside the tyre. I knew I should have taken notes.

I did check all around both beads before inflating to make sure that there's no tube trapped between rim and tyre. I've just had to look up "cornstarch" - it's called "cornflour" on this side of the pond