Sibongile Khumalo, Guildhall Great Hall, London

There is a strong South African presence among the artists at this year's City of London Festival. This is to mark the 10th anniversary of the new South Africa, and within the Gothic splendour of the Guildhall Great Hall, one of South Africa's best loved mezzo-sopranos Sibongile Khumalo is at pains to stress the importance of the freedom that many of her countrymen now feel. Having played at the presidential inauguration of Nelson Mandela, she perhaps feels a sense of history more than most.

There is a strong South African presence among the artists at this year's City of London Festival. This is to mark the 10th anniversary of the new South Africa, and within the Gothic splendour of the Guildhall Great Hall, one of South Africa's best loved mezzo-sopranos Sibongile Khumalo is at pains to stress the importance of the freedom that many of her countrymen now feel. Having played at the presidential inauguration of Nelson Mandela, she perhaps feels a sense of history more than most.

It seems an odd place for the much lauded "Queen of South African jazz" to play. The programme makes much of her classical mezzo-soprano training, and it is at times in evidence in tonight's performance, but fundamentally she is a fine exponent of various township jazz styles, as evidenced by her albums Immortal Secrets and Ancient Evenings. The high arched ceiling does little to lend itself to amplified music, and during the first half the sound engineers fail to stop the vocals and instrumentation sounding somewhat disjointed. The imposing figures of warrior giants Gog and Magog look none too impressed.

Some of the audience seem somewhat underwhelmed. Before the concert starts, I hear a voice saying: "Oh, it's a lady". However the substantial South African contingent in the audience knows exactly who it's seeing, as "Ancestral Voices" and a gospel version of Handel's Messiah struggle to do battle with the hall's booming acoustics. The best moments of the first half occur when Sibongile Khumalo and her backing singers break into wonderful call and response. Khumalo then poignantly introduces a song by saying: "Now the drought is gone, bringing all riches from the land. Finally it feels good to say 'my country'."

Maybe it's because twilight is fast approaching and the space is becoming far more intimate, or maybe it's because of the free wine during the interval, but the second half is significantly better. For a start the sound seems to have been sorted out, and we finally get a real taste of Khumalo's powerhouse vocal range. The audience becomes increasingly appreciative when a fine drum solo is followed by the stunning electric violin virtuosity of Tshepo Mngoma, and a jaw-dropping classical masterclass in vocal dexterity from Khumalo. A song originally penned by the South African pianist Abdullah Ibrahim is swiftly followed by a slinky song about "visas and adult issues", before appreciative South Africans rise to their feet for a rousing rendition of Dark City Sister's "Rosie My Girl".

As Khumalo begins to round off the night she points to her ageing guitarist and proudly states that this is Themba Mokoena. This diminutive figure on stage has a guitar style reminiscent of Wes Montgomery, and shows his credentials on a rousing finale that encourages men in pinstripe suits to do the "Pata Pata" along the aisles.