Alan Bennett The campaign was being supported by playwright Alan Bennett and other well-known people
Campaigners have failed in a legal bid to thwart the closure of several libraries in north-west London.
Residents and celebrities wanted to prevent Brent Council shutting the six libraries.
They hoped the Court of Appeal would overturn the decision of a High Court judge who found the plan lawful.
But judges sided with the council in the case, which is being watched by campaigners around the country where other libraries are threatened.
Lord Justice Richards, Lord Justice Pill and Lord Justice Davis ruled that the High Court judge, after a "most careful and thorough review of all the points advanced", had reached the "right conclusions".
Lord Justice Pill said: "Given the scale of the spending reductions the council was required to make, and the information available following earlier studies, a decision that the library service should bear a share of the reduction was not, in my judgement, unlawful."
He said there was "no doubt" that the council was aware of its statutory duties.
Lord Justice Pill added that a "full consultation was conducted and fully reported to the decision-makers".
The campaigners' solicitor John Halford said the ruling was "difficult to reconcile with what Parliament intended when it enacted the duty that obliges local authorities to grapple with the impact withdrawal of services of this kind has on communities".
He said: "The Court of Appeal appears to accept that there is a risk of indirect discrimination against significant numbers of people in Brent resulting from its plans to impose devastating cuts on local library services.
Closing half of our libraries has had a devastating effect on the most vulnerable members of our community”
End Quote Margaret Bailey SOS Brent Libraries
"But it has excused the council from properly taking that risk into account before deciding to make those cuts."
Mr Halford said they hoped the Supreme Court would now hear the case.
Margaret Bailey, of campaign group SOS Brent Libraries, said: "Our legal team presented compelling evidence of damage to communities from Brent Council's library closures, so we are disappointed that the appeal judges have not found in our favour.
"Closing half of our libraries has had a devastating effect on the most vulnerable members of our community, among them children and families, the elderly, the disabled and those unemployed or on low incomes.
"Brent has always had the means to keep these libraries open, it just lacks the will."
Brent Council said the closures would help to fund improvements to its remaining library service and help it save £104m.
Councillor Ann John, leader of Brent Council said: "We are pleased that the Court of Appeal found unanimously in the council's favour, upholding the decision of Mr Justice Ouseley that the council acted lawfully.
"We will now be able to begin implementing the improvement plan that will deliver a better library service for the people of Brent."
The campaign against the closures was supported by author Philip Pullman, playwright Alan Bennett, singer Nick Cave and bands Depeche Mode, the Pet Shop Boys and Goldfrapp.