The result in Glasgow East told us nothing and it told us everything. Nothing that we didn’t know already and everything about the seriousness of Labour’s predicament. Had the swing to the SNP been a fraction smaller, sending Margaret Curran to Westminster with a wafer-thin majority, the political reality would have been exactly as it is today. In that sense Labour’s defeat was irrelevant. And yet it may prove to have been decisive.

Before John Major imploded and Tony Blair turned British politics on its head, it used to be said that loyalty was the Conservative Party’s secret weapon. Since 1997 that weapon has been firmly in New Labour’s hands. This weekend it is legitimate to ask whether loyalty to the Labour leader isn’t a weapon more likely to do self-harm than to damage our opponents.

For some months, serious Labour people — not the sort to be panicked by a short-term reversal of fortunes — have concluded with regret that Gordon Brown is not only incapable of leading the party to victory at the next election, but that he may well lead us to a defeat so heavy it could take a decade or more to recover. Until now few have said so publicly, but Glasgow East has legitimised a more honest debate about Gordon Brown’s personal responsibility for the party’s predicament.

Not surprisingly, some of the harshest critics are among those most closely associated with Tony Blair. They have been reluctant to express their views for fear of looking like representatives of an embittered minority. Now they can be more confident that their claim to have the best interests of the Labour party at heart will be accepted. The sense of despair has spread way, way beyond the ultra-Blairites.

It is despair mixed with regret rather than anger. The Prime Minister’s analysis of the wider political situation is broadly correct. He’s right to say the problems with fuel and food prices are international ones. He can fairly claim that the government is pursuing the best policies to take the country through the current economic turbulence. Above all, he is entirely justified in saying that the Tories and the SNP have put forward no realistic alternatives. Only the far left, who no longer speak for a significant proportion of the party’s membership, want a significant change of direction.

If Gordon Brown had shown he was able to connect with the British people and win their confidence as Prime Minister, there would be no threat to his leadership. But he has failed that test.

Raising the leadership issue is not “turning inwards”, as some in the Cabinet would have us believe, it is facing outwards, looking the electorate in the eye and acknowledging how they see us. If the voters can’t identify with the leader, they are never going to identify with the party.

On Friday the Prime Minister asked Labour members to “have confidence that, not only do we have the right policies, but that when the time comes we will be able to persuade the British people”. It was an unwise choice of words, inviting the response, “Yes, we believe we have the right policies, but we have no confidence that when the time comes you will be able to persuade the British people”.

Taken with the other electoral tests in Crewe and Nantwich and London in particular, Glasgow East tells us that Labour is failing on a massive scale to get its message across. That much is blindingly obvious. The much harder question to answer is how the party would be faring under a different leader. A lot of things have Labour MPs waking up in a cold sweat these days, but one of their worst nightmares is to oust Gordon Brown, put in somebody more superficially appealing and find that the party’s ratings are as dire as ever.

Given just how hard it is to get rid of a Labour leader who doesn’t want to go, that fear is enough to make most MPs think twice, thrice and still feel paralysed with indecision. Well politics, as Gordon Brown tells us, is about taking the tough decisions.

None of the following propositions can be proved but I believe them to be true. That under a different leader Labour would not have lost the Glasgow East by-election. That a man or woman with different personal qualities would be much better placed to expose the weakness of both the Conservative and SNP alternatives. That a change of leader would significantly improve Labour’s chances at the next general election and avoid the prospect of a defeat so severe that most of today’s ministers would never hold office again.

The risks inherent in a change of leadership are enormous but I believe they are less than the risks of carrying on as we are. Improbable though it is, if Gordon Brown were to stand aside voluntarily he would be greatly admired and thanked for doing so. It need not be a humiliation. He might remember William Hague’s resignation speech after the 2001 general election defeat. “I believe it is vital the party be given the chance to choose a leader who can build on my work, but also take new initiatives and hopefully command a larger personal following in the country,” said a man whose stature only grew after his brave self-assessment. Hague went on to say, “no man or woman is indispensable. No individual is more important than the party”. Wise words indeed.

If the Prime Minister feels unable to make way, then a frank judgement on his liability to the party should be delivered on behalf of more than half his Cabinet thus forcing him to do so. An orderly election for a new leader would then take place, of the sort we should have had when Tony Blair resigned. Gordon Brown could stand if he wished, although he would surely lose.

It would then be for the best of the next generation — David Miliband, James Purnell, Andy Burnham, perhaps Ed Balls — to decide whether to stand. Not to do so would look like cowardice but they might opt to unite behind another candidate, in effect a stop-gap although that could never be admitted. Alan Johnson has the communications skills and human warmth that Brown regrettably lacks and would be a sensible choice.

If Gordon Brown goes with dignity, he will retain the respect of his party as a man who gave it his best shot but was big enough to recognise that modern political leadership requires qualities he just doesn’t have. If he is forced from office or, worse, leads the party to a catastrophic defeat the judgement will be just about as harsh as it gets.

Lance Price is Labour’s former director of communications