On stage were two stools, a table and two glasses of water – a bravely minimalist setting for a historic reunion of Brazil’s two most celebrated singer-songwriters. Caetano Veloso and Gilberto Gil are no strangers to major London venues, but it’s rare for them to perform together. But here they were, each clutching an acoustic guitar and with no backing band, in the city that they were deported to in 1969, after being jailed by the Brazilian military authorities as dangerous musical subversives.

They made no mention of their London exile, but it was reflected in their choice of songs. Gil began with Back in Bahia, an exuberant rocker that he wrote in 1972 when he was allowed back to Brazil, where he would later become minister of culture. Now it was given a slinky unplugged treatment, with Caetano adding vocals and guitar before taking the lead on his lilting Coração Vagabundo. He then switched back to 1967 for Tropicália, once the percussive anthem of the rebellious musical movement spearheaded by himself and Gil, in which Brazilian themes were fused with Western psychedelia or the avant-garde. The new acoustic version still sounded impressively edgy.

The event was billed as “Two Friends, One Century of Music”, and allowed the duo to mix their own songs with favourites by Ary Barroso and Simon Diaz. There was never the sense of experimentation that Caetano showed with his young electric trio last year, but this was a classy and emotional performance. Caetano demonstrated his exquisite and thoughtful vocals on Tonada De Luna Llena, Gil played impressive guitar and provided a powerful, chanting revival of Filhos de Gandhi, and the encores included Caetano’s poignant exile song London, London and Gil’s treatment of Bob Marley’s Three Little Birds. They are now in their early 70s, and they are still remarkable.