The other point, is that it's not only a manifesto commitment that's been broken, but also a much-trumpeted set of personal pledges, many of them (such as Clegg's, which I linked to) held aloft for the cameras while members of the students' union looked approvingly on. So, while Cable may be offering a semi-effective defence of his party, it remains a fact that he and the other individual MPs about the break their individual promises are liars.