One TTL flash, tethered via an TTL cable (10 meters, for Canon, from Yongnuo).
I tried two new light formers here:
1. Traveller8: not my cup of tea (spot too small, light too hard, needs a lot of tape for fixation -- the rubber band does not hold the tool on my flash)
2. Lastolite Mini brolly, 50 cm diameter: works, the shot above was shot with that tool
But any other brolly could do the same or better...
An example for a larger brolly, which can be collapsed and which I like better:
And if I really go on a journey I use a white microbrella (for the rain) with some gaffer tape (for the flash). :-()