I disagree. The fact that it used to be single party government is largely an irrelvance; the important thing is that it is still a constitutional monarchy, parliamentary system, that allows for both coalitions and majority rule. That hasn't changed, and so to say that because we currently have a coalition, of whatever party, means that the position of Deputy Prime Minister should be included alongside the heads of state and government is false. I am all for mentioning Nick Clegg as Deputy Prime Minister in the article, around the same place David Cameron is currently described as Prime Minister, but to put Clegg alongside the Queen and Prime Minister on the basis of it being a coalition government is not right. Now if the job were constitutionally defined as being the Prime Minister's second-in-command, and if Cameron were to die/resign suddenly Clegg would become Prime Minister, I would completely agree that he should be there, but it isn't. Clegg may be Deputy Prime Minister, but he is not deputy head of government, and so he should not be put alongside the head of state and head of government.