Charlotte Church branded austerity "unethical, unfair and unnecessary" as she spoke to a 250,000-strong crowd who gathered in London on Saturday to protest cuts.
In a rousing speech, the singer also gave advice for those whose friends disagreed.
Don’t unfriend all those on Facebook who post things that you disagree with; challenge them, engage them in debate, but kindly and with reason on your side. You never know, you might just change someone’s opinion. And more than anything we need to keep on pressuring the establishment into hearing our voice.
Speaking in Parliament Square, Church described the government's call for austerity as "the big lie", saying:
They will sell off our schools and our hospitals. When it's done, it will be hard to reverse. One aspect of this that really gets under my skin is that it's all wrapped up in a proud-to-be-British package. I'm proud to be British because of the NHS and David Bowie, not because of the Union Jack.
Russell Brand also addressed crowds at the march, alongside Guardian journalist Owen Jones, Unite general secretary Len McCluskey, Green MP Caroline Lucas, and Labour leadership contender Jeremy Corbyn.