Around 300 people packed into the Stand up for the Observer event in London last night to hear Guardian and Observer staff promise strike action if there are any compulsory redundancies at their titles.
The event was organised by the National Union of Journalists, Observer staff and Press Gazette after news emerged seven weeks ago that closing the Observer was one of a range of cost-cutting options being considered by Guardian News and Media to stem losses which last year totalled £36.8m.
Last Thursday, Guardian Media Group announced that it had concluded a review of its weekend publishing operations and said that it was now committed to publishing a "new-look" Observer. But it said the title would be further integrated with the Guardian and that further editorial job cuts would be needed.
Last night joint father of the Guardian and Observer chapel Brian Williams said: "Most of us who work on the papers consider ourselves fairly liberal, but we are not all liberal when it comes to compulsory redundancies. If one single NUJ member is issued with notice of compulsory redundancy there will be an automatic ballot for industrial action."
Last night's meeting at the Friends Meeting House in Euston Road, London, was hosted by comedian and Observer columnist David Mitchell and featured contributions from Observer journalists past and present: Katharine Whitehorn, Barry Norman, Philip French and Victoria Coren.
Coren, who read two pieces by former Observer film critic Clive James, said: "There's a certain type of writing that only works printed in this broadsheet newspaper on a Sunday... in an independent liberal Sunday newspaper that has its own staff that has seven days to put it together, who are not pulled about by other things."
Many of those who attended last night's meeting signed up to a statement which will be handed by the NUJ to the Scott Trust which owns the Observer.
It said: "We were delighted to hear the news that Guardian Media Group management have rejected proposals to close the Observer.
"However, we are still concerned that editorial cutbacks could damage quality at the title.
"We call on GMG management and the Scott Trust to ensure the Observer is maintained with the editorial independence, staffing levels and investment that will rival the leading quality Sunday papers."
One of the Observer staffers who helped organise last night's event told Press Gazette: "It's brilliant that so many people showed up despite the fact that Guardian Media Group said that the Observer name is going to be kept.
"The huge turnout reinforces the fact that this about more than just a name, we really want to make sure that the paper can continue to compete. I've never seen Observer staff so fired up something."
After the meeting Observer staff and their supporters held a party at upmarket nightclub Sketch, off Regent Street.
Among those turning out to show their support were former Observer editor Roger Alton, who now edits The Independent.
He told Press Gazette: "It's a lovely occasion and it shows the great affection that people have for the paper and the intense loyalty of the staff. It shows that newspapers have a great place in people's hearts."
According to some reports as many as 100 of Guardian News and Media's 800 editorial staff may need to be cut to find the necessary cost-savings.
This could open the door for compulsory redundancies.
In November 2007 Guardian and Observer NUJ members agreed a new "house agreement" with management, the wording of which was ambiguous about the long-standing ban on compulsory redundancies at the titles.
It says: "GNM is committed to avoiding compulsory redundancies. Both parties acknowledge that in extreme circumstances reductions in staffing may be unavoidable."