Is your squeegee in good condition, a few nicks in it wouldn't help?
The procedure I go through for prepping the surface is:
• Clean with soapy water, then rinse with clean water (do not leave any traces of soap on the surface).
• Clean away any grease using isopropyl alcohol.
• Dry the surface using clean paper towels which will not leave any small pieces behind, before the isopropyl alcohol has had a chance to evaporate.
You never mentioned cleaning the Rapid Prep off (I have never used this so I don't know what the instructions say). Don't know if this is used much in the UK.
I use kitchen roll for the final cleaning of alcohol, and not towels or rags, as even when cleaned they still hold bits of natural oil and never seem quite as good.