Wendy Alexander faced her MSPs and the media yesterday, trying to explain her U-turn towards support for a snap referendum on Scottish independence.

It came two days after Labour's leader at Holyrood had announced this in a live TV interview, without having agreed it with Holyrood or Westminster colleagues.

What's the big idea?
Ms Alexander wants to kill off the independence cause by forcing a referendum she hopes she can win. With no Westminster election until spring 2010, she is now pushing for an independence poll next year, bringing forward the SNP's referendum planned for 2010.

She has challenged the SNP to accelerate its plans, saying the uncertainty over the issue is harming Scotland. If they don't, she could introduce a Referendum Bill, but she is not saying when.

How could this affect the SNP's plans? Since SNP leader Alex Salmond set out his 2010 timetable, the chances of David Cameron being Prime Minister have soared, which could boost the SNP's case for independence. Ms Alexander claims she can kill SNP momentum by out-flanking them, removing Alex Salmond's argument that Labour was refusing to give people the right to choose their nation's future.

How has the SNP reacted? With delight. They are sticking to the 2010 timetable, saying Wendy Alexander is welcome on to their pro- referendum turf, but that she is so "inept and erratic" that they can't plan on knowing what her position will be next week.

Why did she do this now? A mystery. Perhaps it was because of Labour's terrible council results last week, to stop anti-Labour momentum helping the SNP. Perhaps it was frustration at Gordon Brown for not deciding on a strategy. Perhaps this was policy on the hoof, as her position appeared to change over the TV interview's eight minutes.

What do Labour colleagues think? Some had been pushing to call Alex Salmond's bluff, but this is a big gamble, and no agreement had been reached. The Prime Minister was said on Sunday to be unpersuaded of the plan, then yesterday his spokesman was saying that, while it was the right strategy to put the SNP on the spot, the tactics were a matter for MSPs. Many are exasperated at the way this has been done.

MSPs agreed yesterday to support Ms Alexander, at least in not blocking a referendum. But no-one is impressed by the way she has gone about this. She defends her actions by comparison with Tony Blair when he bounced Scottish Labour into a devolution referendum in 1996, to protest but with the desired result.

What about her plans for more powers under devolution? Sir Kenneth Calman's committee continues to look at the way Holyrood works, having been commissioned to do so by Labour, Tories and LibDem. Those allies had agreed to combine their votes to block an independence referendum before the 2011 election, but the alliance has now crumbled, with Tory talk of "betrayal" and Calman looking by-passed.

How would people vote in an independence referendum? Support depends on the question asked. If the wording is about "a completely separate country", YouGov last month found support at 19%. Less loaded wording has found support over recent years ranging between 23% and 41%, with two recent polls finding support at the upper end of that scale. Support falls if other options are included, such as "more powers for Holyrood", but Wendy Alexander is against complication. Like the SNP, she wants a straight "yes" or "no", despite that increasing her chance of losing.

Isn't this just a storm in a Holyrood tea-cup? Only if it doesn't matter whether Scotland becomes independent or not.