Will Nick Clegg go down in history as the shortest-serving Liberal Democrat leader so far?

His colleagues have shown a tendency for patricide when they felt their leaders weren't up to the job, as Charles Kennedy and Sir Menzies Campbell can attest.

Mr Clegg was supposed to put a stop to that and restore a sense of discipline to his party.

But his bizarre decision to order all his MPs to abstain in last night's key votes on the Lisbon Treaty cannot have helped.

The question facing MPs was whether there should be a referendum on the treaty or not.

Mr Clegg's response was to order his MPs to abstain - in other words, to order them not to have any opinion at all.

Liberal Democrats became "rebels" not just if they voted against the party line, but if they voted for anything.

The official position was that the party had no idea what it thought, and every MP was supposed to follow suit - by refusing to express an opinion.

Perhaps this was designed to avoid an embarrassing split in the party but, if so, there are two issues to raise.

First, Mr Clegg displays a remarkable lack of confidence in his own ability to lead the party if the only way he can keep his troops in line is by refusing to express an opinion.

Secondly, it failed. The party was riven by rebellions and resignations, and Mr Clegg might just as well have adopted a clear policy position, or perhaps given his MPs a free vote.

From Labour's point of view, the Liberal Democrat shambles was a useful distraction from its own minor rebellion.

MPs such as Gisela Stuart, the Labour MP for Edgbaston, have battled through thick and thin to encourage their party to keep its 2005 General Election pledge to hold a referendum.

Gordon Brown, the Prime Minister, argues that the promise no longer applies because the treaty has changed so much since then.

But Ms Stuart, who was involved in writing the original document, insists it is essentially the same.

Her attempts to ensure Labour kept its promise have been described as disloyal by some colleagues, but in fact Labour would undoubtedly gain votes rather than lose them by keeping a manifesto pledge.

Even so, last night's votes mean the battle for Ms Stuart and her colleagues is probably over.

The House of Lords could still ride to their rescue and insist on a referendum but, failing that, the treaty will now probably become law without a public vote.