Originally Posted by Smirnoff

And on the one piece rule, you can take a second piece as long as the second bag fits into the first one (which will then still fit into the gauge) after you have taken out your laptop and liquids. So it's basically one bag, plus a laptop and toiletries, which you then put neatly back in your second bag, immediately after clearing security. There are no further one-bag checks after security, ie at boarding the plane.