A little update for those interested....
I've been using Revita for almost 2 months now I think. A few weeks ago I noticed some tiny, shiney white hairs at the hairline, and I'm sure now they've increased in number - In an area where there previously wasn't any hair.
I'm not getting too excited, they're almost invisible to the naked eye, and could maybe just be the remains of old minaturised hair which despite checking my hair everyday, I hadn't noticed before.
Either way, it's not done me any harm so I'm glad I'm using this shampoo.