I saw this thread title and I knew, I just KNEW it was a Skipy thread. It's a good number mate, and considering the Health and Safety implications of chair stacking in this day and age will be difficult to beat.

I trust that you now carry out the requisite actions of Risk Assessment and Method Statement before even one chair is stacked and then not exceeding the permitted stack height.

There are indications that new European legislation may outlaw the stacking of chairs in any public place.