By Nick Assinder BBC News Online political correspondent

So now we know exactly what the prime minister is supposed to have done to enhance his role during the Queen Mother's lying in state - or some of it.

Someone in Downing Street suggested that Mr Blair and his party might walk from No 10 to Westminster Hall for the occasion instead of driving.

Black Rod has killer memo

That would have taken him through Parliament Square where crowds were gathered to join the mourning.

The proposal was swiftly abandoned and the prime minister drove to the hall.

But not before Black Rod had been told of the suggestion by one of the prime minister's protection team.

Glad handing

And this is where the serious dispute starts. Did, as suggested, Black Rod issue a blunt "no way" order, angry at what he saw was the prime minister's attempt to hijack the occasion.

Or was the plan floated simply because of the difficulty in getting Mr Blair to Westminster Hall through the crowds and closed roads.

The prime minister's official spokesman has comprehensively denied that Black Rod rejected the plan and has stressed nothing was ever done to enhance the prime minister's role.

Officials were eager only to do what was appropriate and within normal protocol, he said.

Campbell close to Blair

In a particularly robust denial , he said it was absolutely wrong to suggest the prime minister wanted to use the occasion to "glad hand" it with the crowds.

The whole row, he insists, is over the interpretation of conversations between Downing Street and Black Rod.

There will now be huge pressure for the so-called "killer memo" compiled by Black Rod over the affair to be published.

In the frame

The latest twist comes as the row over government spin has continued to escalate.

And there is a widely held view that, whatever the rights and wrongs of the allegations, the prime minister's spin doctor in chief, Alastair Campbell, is now the man in the frame.

It was Mr Campbell who originally took the case to the press complaints commission - before it was effectively abandoned last Tuesday - and who is at the centre of the allegations about out-of-control spinning.

Born-again leftie Roy Hattersley has led the demands for his sacking and the idea is gaining ground in Westminster.

Becoming the story

Mr Campbell recognised the danger himself some time ago.

He saw that, like Gordon Brown's man Charlie Whelan before him, he was becoming the story.

He decided, as a result, to remove himself from the front line. It was spun as the beginning of the end of spin.

In fact, apart from the lack of personal appearances, very little changed and his influence is as pervasive and powerful as ever it was. But now, he is under fire like never before.

And, with Peter Mandelson and Stephen Byers gone, there is the feeling that attention will now be focused exclusively on him. But his detractors should not hold their breath.

Tony Blair is virtually joined at the hip to Mr Campbell and to sack him would severely, possibly fatally, wound him.

It would be seen as a massive admission of guilt from Mr Blair himself and the final confirmation that New Labour has been "all spin and no substance".