Exit Byers, with spin control to the end

Stephen Byers gave no sign of wanting to resign at the weekend, despite having his record as Transport Secretary savaged by a Labour-dominated select committee.

His aides were enthusiastically briefing on his behalf, claiming that he was to tear up the £180 billion 10-year transport plan announced only last year by Deputy Prime Minister John Prescott and have a new version ready by July.

Just a day later, according to senior sources, he told Tony Blair in a Downing Street meeting that he wanted to quit. The truth probably lies, as so often in politics, somewhere between the two extremes.

Mr Byers had become increasingly fed up with headlines proclaiming him a liar and could see no end in sight. At the same time, those closest to Mr Blair had also become fed up, and were doing their best to persuade the Prime Minister to sack his beleaguered Transport Secretary, or at least shuffle him to a lower-profile Cabinet post.

The Prime Minister, it is understood, would have done so in a planned July reshuffle. But Mr Byers told him at Downing Street on Monday morning he was inclined to go - and he met little if any resistance from Mr Blair. The two men met again between 3pm and 4pm the same day and the mechanics of Mr Byers's departure were agreed.

Why Downing Street?

One of the highly unusual features of Mr Byers's resignation was its high-profile, on-camera announcement by the minister himself in the ornate Pillared Room at No10.

Normally, resignations are made public by government press release, accompanied by "Dear Tony" letters - not done immediately in this case. Instead, reporters were told to come to Downing Street with little or no advance warning, and merely told that a big event was taking place. Sources suggest-that an element of "spin control" - an addiction to which helped send Mr Byers to his downfall - was in operation and that Downing Street's expertise in staging lightningfast media events was very useful.

As Mr Byers read his statement - he took no questions afterwards - Mr Blair's all-powerful communications chief Alastair Campbell lurked almost unseen in the background.

Staging the event at No10 also allowed Mr Blair to make a friendly gesture towards Mr Byers, who had been one of his key allies since Opposition days, even though the Prime Minister himself was not present as he was returning from a Nato summit in Rome.

Why now?

The resignation came at the end of a particularly grisly month for Mr Byers, which featured the continuing charges that he had lied over the "resignation" of his press chief Martin Sixsmith, the Potters Bar rail tragedy, his trial by the transport select committee and his gaffe when he blurted out the Government's preparations for membership of the euro over lunch with lobby journalists.

However, two other factors were probably more important. First came an opinion poll - - continuing obsessions for New Labour - which showed Mr Byers plumbing new depths of unpopularity while also, crucially, appearing to drag Mr Blair's ratings and those of the Government down with him.

Next came the imminent date, next week, when Mr Sixsmith officially ceases being an employee of Mr Byers's transport department, though in practice of course he has not been at his desk for weeks.

Some senior figures are thought to have feared that Mr Sixsmith's "friends" would take the opportunity of revealing further murky details of his time working for the ex-Transport Secretary, including possibly a "smoking gun".

Another reason for staging the departure this week is that the Commons is not sitting and MPs are absent, lessening the chances of sensitive resignation announcements and reshuffle details leaking out through Westminster gossip.

The unanswered questions

Stephen Byers declared in his resignation statement that there were "some things I would have done differently." What are they?

Could this be a reference to his decision not to sack his spin doctor Jo Moore immediately after details emerged of her notorious 11 September email calling on colleagues to seize the opportunity to "bury" bad news?

If she had departed quickly, the cycle of scandal and blunder that subsequently engulfed Mr Byers and his department could have been stopped in its tracks.

But he clung on to her, and was significantly supported in doing so by Mr Blair.

Mr Blair's statement said that " much" of the criticism directed at Mr Byers had been unfair. Which parts were not?

Was this another reference to his stubbornness in holding on to Ms Moore and a tacit admission by the Prime Minister that he should have insisted on her scalp?

Does it refer more widely to the general spin rows involving Ms Moore and Mr Sixsmith which paralysed his department and put its permanent secretary, Sir Richard Mottram, on the rack? Could it even be an admission by Mr Blair that Mr Byers had been economical with the truth in his statements to MPs and his media interviews?

Other questions, no less fascinating, concern the key policy areas overseen by the departed minister.

How long must we wait for a successor body to Railtrack, which Mr Byers claimed would be ready in the autumn? And what is the future of the Tube, with final part-privatisation contracts still not signed?