I didn't use the lemon juice as cannot think of one possible reason why this would help, despite S & G saying to the contrary. 
I have been living in my boots and decided today was the day to try this file and my feet are brilliant now. It is even better than my all singing and dancing one that I got from QVC for 21 quid...
Mrs CB - well, shucks Maybe not as good as others but y'know ...
missF - they had loads in store in the fairly large Boots I went to. Not available online now?