I had a mate who used to carry around a bit of broom stick cut to the exact length to do the same as Robin. Very useful in keeping the TTR upright when removing/replacing the rear wheel
I usually end up scrabbling around the nearest hedge for something to use.
No more info on Robin's trip - sorry - just the photos.
Looks like he has got his propped up under the bottom of the frame somewhere. I might make something up. Probably a bit better than using a mates front wheel!