We had a rabbit problem some years ago until a combination of cats and the accidental digging up of their warren for soil replacement seems to have got rid of them, for the time being at least. They were very destructive and we lost many seedlings, an Aloe vera and worst of all some trees, as they gnawed off the bark at the base of the trunk. We had to resort to protecting everything we planted with plastic netting. I can well imagine you were not too pleased, Andrew, to lose your precious Filippi plants.
It is good to have another weapon in our armamentarium against these cute but voracious creatures. It would indeed be very useful to know how long the hair treatment remains effective.