I'm not sure of the origin of the phrase "elephant in the room", except that it is American and applies to issues which are so large that only the most blinkered could fail to see them. Well, someone has finally spotted that the world's largest land mammal is sitting in the Scottish Labour Party's living room. His name is Tom McCabe.

"No ifs, buts or maybes," said the former Labour parliament minister in yesterday's Sunday Herald. "Whoever takes over as leader of the Scottish Labour Party has to be in complete control of the organisation and policies that best suit Scottish circumstances." In other words, the Scottish Labour leader has to become the real Scottish leader, with full autonomy and authority over policy in Scotland, without always having to look over their shoulders at Westminster. At last someone has had the courage to state the obvious.

You would think that, after Glasgow East, Labour MPs, too, would have started to notice the flapping ears and the tusks, but no. The leadership candidate, Andy Kerr, was accused of "nationalism" last week just for suggesting that the Scottish leader's powers should be "beefed up". London Labour wants the Scottish leader to remain merely the titular leader of the MSPs in Holyrood, a docile and subordinate figure who has to lift the phone to Gordon Brown in cabinet meetings to be sure he isn't getting out of line. And, yes, that really did happen.

Tom McCabe isn't supporting any of the candidates in the current contest and it's just as well because he would never have been able to write his remarkable article, which is essential reading for anyone with the remotest interest in what happens to Labour in Scotland. He is reflecting the views of countless disillusioned Labour voters and activists in Scotland who have been yearning for a lead from someone of influence in the Scottish party and who are fed up with what McCabe calls "the obscure language of prevarication that the public can see right through".

McCabe has not had a reputation for strategic thinking or intellectual brilliance, but his analysis of the constitutional deficiencies of the Scottish Labour leadership is devastating in its directness and clarity. He has said what Wendy Alexander never managed to say. It is the most important Labour strategy statement in decades, and should be nailed to the door of every Labour constituency association in Scotland.

The kind of leader Labour needs, says McCabe, is one who is able to "say and do what is best for Scots, no matter who it might upset. A leader," he goes on, "who is prepared to publicly ask the government in Westminster, irrespective of its political colour, why companies such as Shell can make £8bn profit in six months, while Scots can scarcely afford to fill up cars and vans. A leader who wants to have responsibility for raising the money their government spends and be chastened by that accountability in the process. Finally, a leader who accepts that the council tax has become an unfair burden and set a firm timetable for abolition." Wow! When have you ever heard any Labour MSP talk like that before?

McCabe will, of course, be monstered by his colleagues in Westminster for these heresies. But he's ready for them. "For too long," he says, "there have been Scottish Labour politicians at local government level and at Westminster who have been resentful, and even contemptuous, of the Scottish Parliament. That behaviour needs to stop." He's absolutely right. This attitude goes back a long way, to the time when Labour regarded the Scottish Parliament as little more than a device to undermine the SNP.

Labour MPs cling to an anachronistic notion of their own constitutional superiority. But, you have to ask, who are these people? The days when the Scottish Labour group in Westminster was composed of Donald Dewars and Brian Wilsons are gone. They should take a look at themselves. In fact, the voters of Glasgow East did precisely that - took a long, cool look at their own MP of 30 years, David Marshall, and decided that they wouldn't be fooled again.

For the past decade, Labour MPs have sat around Westminster claiming generous expenses and feeling self-important, while most of the issues that concern their constituents are handled by the MSPs in Holyrood. The truth is, many of the Scottish Labour group in Westminster would find it very hard to survive in the rough and tumble of the Scottish Parliament. Look at Lord George Foulkes, the former Labour cabinet minister turned MSP, who has just won the paranoid buffoon of the year award for claiming that painting ScotRail carriages in the colours of the Saltire amounts to "brainwashing" by the Nationalist government. Labour's MPs have very little cause for self-congratulation: the fact is that if Glasgow East was replicated across Scotland, the only MP left north of the border would be Tom Clarke; that tells you all you need to know.

Tom McCabe could probably do without my endorsement, since it will only help his critics to tar him with the brush of "proto-nationalism". But I think he can look after himself, as he has done for nearly a decade in the front line of Scottish politics. One of McCabe's achievements was making the case for the smoking ban, and putting backbone into Jack McConnell in his battle with the Labour establishment over the policy. The ban was opposed by many Labour MPs as an electoral liability. It turned out that the ban was the greatest single legislative achievement of the Scottish Parliament, one of the few truly lifesaving policies to be implemented by either parliament, north or south, in the past 30 years. And, of course, Westminster ended up following it.

McConnell could tell you of a dozen similar episodes, which didn't end so happily - where Westminster vetoed his attempts to get Labour into contention in Scotland. Over Iraq, Trident, asylum, immigration, attendance allowances and many other policies, McConnell struggled to free himself from a UK party line that was politically ruinous in a Scottish context. Perhaps the greatest fiasco was the council tax fudge at the Scottish election campaign in 2007, when McConnell was forced to defend a "reform" of the policy which was so incoherent he couldn't explain it at its press launch. The former First Minister wasn't even allowed to recognise that Labour had lost that election, such was the myopia of his Westminster minders.

Well, at last a line has been drawn under all that. Tom McCabe has provided a rallying call for all those in the party who want to save Labour from itself. But the first thing they have to do is recognise the nature of problem. It's time for others in the party to get out the elephant gun and take aim.