Protesters have staged an all-night sit-in at a library in south-east London against planned closures.
Campaigners against cuts at New Cross Library occupied the building on Saturday night and left at lunchtime on Sunday.
One demonstrator said he hoped this would be the start of more protests over library cuts.
Groups held "read-ins" and storytelling sessions at dozens of UK libraries on Saturday.
Philip Pullman and Mark Haddon were among a number of authors taking part in the national day of action on Saturday.
A group of about 15 people from the Save New Cross Library Campaign staged the all-night sit-in.
Protester James Holland, who spent the night at the library, said: "There is always a buzz when people cross over a little line and do something for themselves. It makes them feel empowered.
"The libraries are a big issue anyway but this shows that people can do something more. I just hope that this is the start of something rather than the end.
"Shutting libraries is a grave mistake for many local authorities."
A spokesman for Lewisham Council said: "Government cuts mean that we have to find savings of £88m over the next four years. The proposal to relocate some library services is just one of these.
"We appreciate people do have the right to express their opinions and demonstrate and we're not entirely surprised parts of the community feel strongly about this.
"We have carried out extensive public consultations on this and we do have to wait until the mayor makes a decision on library provision on 17 February."
More than 450 libraries and mobile services across the country are currently threatened with closure.
Some councils have said keeping libraries open would put services for vulnerable and elderly people at risk.
Lauren Smith, spokeswoman for Voices for the Library, said yesterday: "Local councils are having to make these decisions so quickly. Once a library is shut it will never reopen. When councils realise what they have done it will be too late."
Mr Holland suggested the council's elected mayor and executive directors could take pay cuts, but added that central government was "not off the hook".
"As far as I'm concerned there's money available all over the place, whether it's from tax-dodging corporations or if its bureaucracies in councils. I think the people who have really failed here are the politicians, it's a total failure of democracy.
"We need to save all public services and we don't need to cut any of them. I don't understand why people aren't looking at the genuine alternatives to fund public services and to getting the money from the people who can afford to pay it - that's exactly the answer."
'Narrowing of horizons'
Other events during Saturday included a rally outside Bolton's central library and a flashmob book reading at Cambridge Central Library.
Musician Billy Bragg sang and delivered a speech in Dorset, where library users attempted to take out the maximum number of books to empty shelves.
Children's author John Dougherty was among those attempting a mini-marathon "I love libraries" tour through Gloucestershire.
Glasgow-based children's author Julia Donaldson delivered a statement of protest to the Scottish Parliament in Edinburgh.
Comic writer Gervase Phinn sent a statement to Bawtry library in South Yorkshire, describing books as "the architecture of a civilised society".
He added: "Reading is the very protein of growth in learning. We must preserve our libraries."
His Dark Materials author Philip Pullman has been particularly vocal over proposals to close 20 of Oxfordshire County Council's 43 libraries.
He said the impact would not be easily measured. He said: "It's a kind of inward loss, a darkening of things, a narrowing of horizons that will gradually make us a less informed, less intelligent, less aware, less useful, less imaginative, less kindly people than we might have been."
But in a letter to the Guardian, Keith Mitchell, leader of Oxfordshire County Council, said the authors' calls to exempt libraries from cuts was "a call to heap more cuts on care of the elderly, learning disabled and those with mental health problems".
"Have they thought through the impact of their messianic message about literature on the most vulnerable in our society?"
Oxfordshire County Council defended its proposed cuts to libraries, saying it, like other councils, had a requirement to make "significant financial savings" to its budgets.
Doncaster is planning to axe 14 out of 26 branches, including Bawtry. Doncaster's mayor, Peter Davies, said he regretted having to cut funding to libraries, but said he was morally obliged to continue other vital services.
"Something that affects people's lives on a daily basis or turns them upside down completely, as you would if you closed an old folks' home, is totally unacceptable to me.
"Libraries are used by about 16% of Doncaster people and many of them not on a regular basis - it is unfortunate."