I used this stuff to cover the grease stains, etc, on my kitchen walls. Just put it on with a roller as normal and then emulsion over. :thumbup
http://www.tesco.com/direct/polycell-sta...lsrc=aw.ds
http://www.tesco.com/direct/polycell-sta...lsrc=aw.ds
I could change my opinion, but then we'd both be wrong.