When Joan Baez telephones me from California (OK: that’s just how the interview was organised), she had just finished making breakfast for her 98-year-old mother.

She told me she’d recently been looking to buy a cassette recorder on eBay.

I rather like this homely image of today — so different from that of the singer with a voice of bell-like purity who lived with Dylan and marched with King in the 1960s.

A scarcely believable 71, Baez comes to the New Theatre on Monday, March 19, and will surely sing those great protest anthems with which she is so connected.

“I would say the feelings that go deepest,” she told me, “are about social change, and music has been my route to get there. I’ve always been happiest when I had both hats on at once. Sometimes when there hasn’t been something going on under my feet, as it were, I feel a little bit hollow. But then I have to deal with that: I can’t create a cause for myself.”

Last autumn in New York, she played a few songs for the Occupy Wall Street movement and is immensely enthusiastic about that cause. “I find it very hopeful. Few people today are prepared to risk much of anything, but these kids are willing to go to jail, and that sort of thing has not happened, literally, in decades.

“Their job is harder than bringing down a dictator: that’s just one goal. But here, they have so many goals. This country’s huge and corrupt and the legacy of the kids is so bizarre, picked up from the Reagan years of nothingness”.

And immediately it’s the classic Joan Baez speaking: “Most kids these days don’t have any sense of history. I did an interview for a little movie on Cesar Chavez, and they didn’t know anything about the farm workers, about life in the fields. At a concert not long ago, I told a story about Dr King and dogs being set on children — and apparently afterwards some of the kids said to their parents, ‘Was she just making that up?’ “If these guys could learn more, that would help. On the other hand, if you say ‘Pete Seeger’s going to come over and visit tomorrow’, they get so excited — that surprised me!”

Baez kept out of American party politics for decades until coming out for Barack Obama four years ago. When I ask if she’s been disappointed, the answer doesn’t surprise: “Very. If you set yourself up for something and it doesn’t happen, then you’ll be disappointed. It wasn’t a surprise at all when everything went to seed. His greatest strength may be in speaking, but there’s a little streak in him that seems not quite courageous enough. I think we’re all hoping that he may snap out of it.” She sounded dispirited.

To a happier subject: her voice. I was surprised — and impressed —that in the credits on her last record (Day After Tomorrow), Baez thanks her two vocal coaches: it is, after all, at the root of what she does.

“If I didn’t work with them, I wouldn’t be singing. When I started, I never dreamed I would ever need help with anything — certainly after I got started and was considered sort of ‘Miss Natural Talent’. But the vocal chords are muscles; if you don’t work them properly, they’ll just start going South on you. I figured that out when I was 35, when I was having trouble with some notes and I didn’t know what that meant! Somebody said, ‘Why don’t you go to a teacher?’ and I replied, ‘Ha-ha, me?!’ Two years later, I went.”

I don’t know, by the way, if any other of the thousands who have interviewed Joan Baez over the years have elicited the information that one of the important things she rebelled against all those years ago was Elvis’s How Much Is That Doggy In The Window?

Joan Baez stars at the New Theatre, Oxford, on March 19.