During the days of the Cold War when the Soviet media was a branch of its government, a band of people emerged to interpret for the West the real meaning of the most minute developments in Soviet corridors of power.

Known as Kremlin watchers, they could analyse the briefest announcements of a new sacking or appointment and predict potentially monumental change ahead for the world.

In Britain today we have a free press but no effective Opposition so the biggest worry for Tony Blair is the enemy within. As a result, Downing Street watchers rightly view any changes not only in the context of promotion and demotion, but also in the struggle for power.

I cannot help thinking that there is more to the resignation of Clare Short than meets the eye. Indeed it wouldn't surprise me if it precipitates a battle for the leadership of the Labour party within the next 12 months.

If Clare Short felt the need to resign on principle why didn't she do so at the time the Prime Minister agreed to go to war in Iraq without the support of a second UN resolution? Could it be that with the country on the verge of conflict and Robin Cook having resigned, Ms Short and her supporters were worried such a gesture would not attract the long-term media glare they sought ?

The timing of Ms Short's resignation is interesting. Despite a week of coverage I can guarantee Ms Short and her views will still be given a full airing in this Sunday's press.

It is reminiscent of the devastating speech Geoffrey Howe delivered on the floor of the Commons in which he lambasted Margaret Thatcher and launched the leadership battle that ousted her. He finished his resignation speech by effectively saying he had done his bit and now it was time for others to come to the fore.

History has repeated itself. Ms Short has sparked a leadership challenge. Think of her as a winger in football crossing the ball for someone to ram home into the goal. The lurking centre forward is, of course, Ms Short's friend Gordon Brown. A man she admits confiding in before making her decision to quit.

The Chancellor already carries substantial support within the Labour party and in recent days his mathematical brain may have wandered from the country's finances and on to totting up how many extra votes Clare Short's supporters will bring to his leadership aspirations.

Of course Mr Blair has proved a successful and popular Prime Minister and will be boosted by success in the Gulf. Mr Brown needs a credible reason to challenge him.

That reason increasingly looks likely to be the question of when to hold a referendum on Britain joining the euro. Mr Blair apparently believes one could be held in the near future whilst Mr Brown believes it should not be held before the next election. The two men are on a collision course which could end in a battle for the leadership of the Labour party.

I suspect Ms Short will be holding another couple of press conferences in the coming months.

One will see the launch of her book about how Tony Blair supposedly betrayed his party. The second will see her lining up as a principal supporter of Gordon Brown in a leadership challenge.