Joan Baez let slip early on that this might be the last time she undertakes such an extensive tour.

The thought will be a terror for anyone who missed this magical Brighton Dome date.

More importantly, such is the dearth of new folk singers with anything valuable to say, it is a graver threat for those who believe music has lost its way, become cynical and empty, and no longer stands to educate as well as entertain.

While Baez’s voice has dropped a couple of keys, she sung with the same subtlety and power as the energetic 18-year-old folk-obsessed activist who moved to Boston to sing in its coffee houses in the late 1950s.

And with her high cheekbones and golden skin, she looked 20 years younger than most 71-year-olds. The secret: she has an optimism few in their teens can match.

She eased through 25 or so numbers from across the back catalogue, playing tracks such as The Scarlet Tide, Diamonds And Rust, There But For The Fortune and The House Of The Rising Sun. But it wasn’t until late in the set, and Gracias A La Vida, that the audience got involved, with Baez and virtuoso multi-instrumentalist Dirk Powell (here throwing in acoustic bass solos after piano, violin, accordion and banjo) singing to celebrate life.

Of course, age is an irrelevance with the power of a simple eloquent message put to music. So it was fitting that John Lennon’s Imagine, with its timeless melody and enduring lyrics, induced the first of three standing ovations.