The Daily Telegraph has cited a blog from the Adam Smith Institutes' Head of Projects, Sam Dumitriu, on airport liquid restrictions:

According to the Adam Smith Institute, one of the world’s leading think tanks, current restrictions would not prevent determined terrorists from getting liquid explosives through airport security.

“Indeed, the very basis of the restrictions seem weak,” it said, in a recent blog post.

“Even if a would-be terrorist wasn't able to bring enough of an explosive on board as part of their liquid allowance, they could still buddy up with a couple others troublemakers and simply mix the explosive liquids together in a bigger bottle bought in duty free.”

Sam Dumitriu's blog post can be read in full here.