I then place a off cut of rain downpipe into the hole so when i pour the concrete the hole remains.
I place the reo and reo-props before laying the concrete.
All done, I let it set for a couple of hours and wiggled the downpipe a few times, Th enext week it was very easy to pull out. Another idea is to line it with plastic wrap, the wrap will be easy to peel off the cement. 