This is a simple extension of the excellent xticklabel_rotate code from Brian Katz (originally Denis Gilbert) to work on graphs with two axes.
thanks to a kind user, please see the following correction to the code:
line 129: %check that we have label for each XTick
line 130: if size(XTick,1) ~= size(xTickLabels,1),
line 131: error('xticklabel_rotate : must have same number of elements in "XTick" and "XTickLabel"') ;
line 132: end