Thanks for the tip about isopropyl alcohol for stains. After a vase of lilies fell over onto our cream carpet (I know, we were asking for trouble), there was a stubborn yellow stain which was resistant to all cleaning solutions known to mankind. I'd tried everything: Vanish, stain remover, carpet cleaner - but a trip to Maplins for a £9.99 can of the stuff meant that I was spared the hassle of an insurance claim. I just sprayed it on and mopped it up with kitchen roll. Job done!
I have got two bright yellow lily pollen stains on my beige carpet, which despite washing with water and treating with several doses of Vanish refuse to disappear.