Musical-theatre singers are in an odd position: they need to be distinctive but not too distinctive, powerful but not eccentric. The Filipina singer Lea Salonga has been striking this balance perfectly on Broadway and West End stages since starring in Miss Saigon 30 years ago, aged only 18. She sings with perfect diction and “acts out” every lyric she performs, but her secret weapon is a fierce yet controlled vibrato. It rarely strays beyond a few microtones either side of the principal note, and, unlike an opera soprano’s vibrato, retains an intensity and focus that never detracts from the melody.

As well as performing songs from musicals in which she has starred – Aladdin, Mulan, Les Misérables and Miss Saigon – her actorly skill ekes new truths from familiar showtunes and pop standards, such as a duet arrangement of A-ha’s Take on Me for voice and acoustic guitar, or a conversational version of Tracy Chapman’s Fast Car.

But, in her slightly schoolmarmish way, she’s also a fine master of ceremonies. She orchestrates the audience to sing the backing vocals to This Is Me from The Greatest Showman; she turns Frozen’s Let It Go into a Disney singalong: when one gay man in the audience responds to the line “and it looks like I’m the queen” by standing up and whooping “Yas queen!”, Salonga responds, like much of the audience, by applauding and giggling hysterically.

Memorably, she invites a random man from the audience to duet with her on A Whole New World, with tonight’s lucky winner being Mark from Salonga’s home city of Manila. “Thank you for perpetuating the stereotype that all Filipinos are great singers,” she says, drily.