By BBC News Online's Nyta Mann

She's been a long time coming but the Glenda Jackson everyone was looking for is back. And this time she's angry.

When the double Oscar-winner entered the House of Commons in 1992 commentators thought she would add stardust and passionate drama to Labour's benches.

So it was a grave disappointment to some when the woman seen on the big screen cavorting in actorly fashion with Oliver Reed instead knuckled down to the task of becoming a common or garden constituency MP.

And then after the 1997 election, two unflamboyant years as a junior transport minister solidified a reputation for being dour and grimly loyal to the New Labour leadership.

Since entering the contest for Labour's London mayoral nomination, though, the passionate, don't-give-a-damn Jackson observers had given up looking for has emerged.

Last summer she was assiduously wooed through anonymous press briefings from "sources close to Tony Blair" to throw her hat into the ring to become Labour's mayoral candidate.

By the autumn the party hierarchy had decided to back late entry Frank Dobson instead. The non-stop farce surrounding the selection contest ever since has turned the star of Women in Love into woman in a strop.

Beneficiary of Dobson's woes?

The latest spin from unnamed Labour sources now has it that Jackson could end up the beneficiary of Blair's disappointment at Dobson's flagging campaign.

If the former health secretary's bid to win the nomination fails to shape up soon, Labour's Millbank machine could drop Dobbo to instead swing its might behind Jackson as the candidate best placed to challenge left-winger Ken Livingstone.

"Well they haven't spoken to me about it," Jackson declares. Has no prime ministerial emissary been in touch? "None whatever!"

If there was disappointment at Jackson's early performance as a politician, it's clear she isn't overly impressed with the practitioners of the trade. I ask her if she found more prima donnas in politics than she did on the stage.

"Oh yes," she unhesitatingly answers. "Certainly, yes. Because one of the things I always find interesting about the perceptions of acting and the theatre is that it is full of undisciplined people who let it all hang out.

"It is much too hard a profession, the work is much too demanding for that kind of behaviour ever really to be found acceptable. Acting is a very hard thing to do and it's an extremely disciplined profession. It has to be if you're going to take money from the general public eight times a week - you have to be able to deliver those performances every single time."

We are on the Heathrow Express travelling to a GMB union hustings meeting being held near the airport, at which all three Labour hopefuls will speak.

As well as being accompanied by BBC News Online, a camera crew is also in tow this evening, filming from every possible angle everything Jackson gets up to. Except smoking, which she does often but sternly instructs the camera not to capture.

With ballot papers due to be sent to Labour members at the end of the month, Jackson has been campaigning non-stop for weeks now. Given her fierce denunciations of the internal party jiggery-pokery widely alleged to have gone on during the selection, wouldn't she feel a turncoat if the party leadership suddenly anointed her its chosen candidate?

"I think it's highly unlikely," she says, airily dismissing the possibility. "It's a hypothetical question."

Private cabinet support

She has, she says, had private messages of support from cabinet members, though she won't say from whom - "because I'm not going to create a situation where there could be stories running of splits in a Labour cabinet."

Things aren't much better in the Parliamentary Labour Party, where just a single MP - Ealing North's Stephen Pound - has been bold enough to nail his colours to Glenda's mast.

What does she put this down to? Gutlessness on the part of MPs scared of attracting the disapproval of party managers? "You tell me," is her waspish reply.

Once at Heathrow it's a quick bus-ride to the hotel where the first of the evening's meetings is being held. Jackson arrives just as Dobson is climbing out of his car. He greets her with a cheery "Hallo darling!"

Ken Livingstone is already in the hotel foyer. A spot of amicable three-way bickering takes place over how best to travel to the meeting after the one about to start.

When it does, the GMB audience gets to hear each candidate deliver their by now well-practised why-I-should-be-mayor pitch.

Perhaps unsurprisingly given the trade union audience, an invitation for questions from the floor attracts protests that the government has failed to do enough for working people - with Dobson on the receiving end of the more hostile inquiries. ("Every single member of that audience bar one was an SWP member!" he later complains.)

Rival assessment

After little more than an hour, it's straight on to the next meeting - a joint gathering of Islington North and South constituency Labour parties. Jackson and Livingstone catch the train back into central London while Dobson takes his chances with the Tube.

The two are happily chatting away, trading tips and latest information, so I ask Jackson what she judges to be the strengths, if any, of Livingstone's bid to be mayor. With her rival guffawing in the seat next to her, she carefully answers: "Experience, by virtue of being with the GLC. The ability to speak very immediately to an audience. And I think they're big strengths."

Livingstone returns the courtesy: "Everyone I speak to thinks Glenda has been the one who has won the debates when they see us on television. Me and Frank have been around so long in so much old hack politics that nothing shocks us. Glenda is still visibly angry when things happen that shouldn't . . . I go home at night and my partner says to me 'Glenda won that one!'"

On the subject of Dobson's campaign, Jackson adopts a best-not-to-dwell-on-it tone: "Well, I mean, they've had to launch it three times. I think that speaks for itself, really."

'They've been in the pub'

A small reception committee is waiting at Highbury & Islington Underground station and chaperones us to the meeting. "There probably isn't a floating voter in the room!" one of the group making its way to the venue predicts.

"Oh I don't know - they've been in the pub a while," another seeks to reassure.

Perhaps as a consequence, this meeting is a much livelier affair than the earlier hustings, with standing-room only and 400-plus party members in attendance. The three hopefuls once again deliver their vote-for-me appeals, this time tailored to the north London audience.

As at the GMB meeting, Jackson stresses that much more unites the three than divides them. "You couldn't get a cigarette paper between many of our policies," she insists.

The key point of difference remains the government's planned partial sell-off of the London Underground. Livingstone is firmly opposed. Dobson and Jackson are in favour - though it is hard to see how any private doubts could be expressed since the two loyally backed the policy while ministers.

Afterwards, outside the hall and as Jackson rummages in her bag for another cigarette, she pronounces the evening a success. "What I quite often get is surprise from people at these meetings - they don't think I'm actually as au fait with the issues as they realise I am by the end of them."

She's been doing them for weeks now, and the grinding schedule of several such meetings a day stretches well into next month.

"Yes, it is relentless," she concedes between drags on her cigarette. "But I enjoy it, I like campaigning - and for me these meetings are encouraging."

At this point Dobson, who has spent recent weeks attempting to shake off the accusation that he has been plunged into depression by the lack of progress his campaign is making, exits the hall to make his way home. Deadpan, Jackson seamlessly continues: "If they were other than encouraging, I suppose it might be different."

The Glenda Jackson everyone was looking for is back.