Alexandra Burke, Union Chapel, London

Sitting in the pews of the beautiful Grade II-listed Union Chapel, the drama of The X Factor could not seem further away. Yet, as the country remains gripped in the weekly twists and turns of Simon Cowell's singing competition, this 19th-century chapel is tonight the venue for the first proper headline show from Alexandra Burke, last year's victor.

With a number one album and two number one singles achieved since defeating JLS and Eoghan Quigg in last December's final, 2009 has treated Burke well, and this appearance as part of the Little Noise Sessions – a series of stripped-down concerts for the charity Mencap – is a further sign that she is developing into a fully fledged star in her own right.

Tonight's show begins with VV Brown, and her impressive voice works well with her acoustic backing. She is followed by Alphabeat, and the Danes' infectious Europop can't help but put a smile on the faces of the crowd.

If any of the current X Factor finalists had been in the audience they would have had some interesting points to ponder. With only a matter of weeks left in the competition, it may be time to start considering what kind of winner this year will produce – is there a Leona Lewis left in the remaining acts, or are they a bunch of Shayne Wards and Steve Brooksteins? From the moment Burke launches into "They Don't Know", it is clear that her voice sets her firmly in the former camp. Born and raised in Islington, this is very much a home gig for the 21-year-old, and during the song she acknowledges the presence in the audience of her mother, brother and father.

She is a natural with the crowd and really seems to feel the emotion, welling up after "The Silence". For the most part she sings to a backing tape, accompanied by two male vocalists, and although it would have been interesting to see her perform with a band, it does mean the focus is on her voice. For her rendition of Leonard Cohen's "Hallelujah", she is joined by an acoustic guitarist, and as a result, the subsequent version is a measurable improvement on the single she released.

She finishes with the incredibly catchy "Bad Boys", which starts off as a slow, stripped-down reimagining before launching into its usual form. She leaves the audience mightily impressed. This year's X Factor hopefuls have quite an act to follow.