The Spice Girls in their heyday in 1998

She and Emma will sing I Know Him So Well from the musical Chess.
Mel added on Twitter: 'Me and @EmmaBunton and have recorded the fantastic,'I know him so well' Singing together again is amazing and emotional. Love you baby! x.'
Also adding to their Tiwtter exchange was Jennifer Saunders, who joked she had sung it better with her comedy partner Dawn French.
The pair's duet comes less than two weeks after they reunited with bandmates Melanie Brown, Geri Halliwell and Victoria Beckham in London to unveil the new Spice Girls musical Viva Forever!

Reunited... for a photocall: Mel C and Emma with their former Spice Girl bandmates Melanie Brown, Geri Halliwell and Victoria Beckham on June 26

However, despite the photocall, there appears to be no sign of the Spice Girls planning to perform or record together.
The five-piece last recorded together in 2007 on the one-off single Headlines (Friendship Never Ends) - the only new release from their greatest hits album - which peaked at No.11 in the UK singles charts.
The track coincided with their sell-out Return Of The Spice Girls world tour, which ended prematurely after they cancelled the gigs in South America, South Africa and Asia, citing 'family commitments'.
Over the past few years, Mel B has often hinted of a possible reunion for the girl group, but it is yet to come to fruition.

The way they were: The Spice Girls in their heyday in 1998

However, Victoria was said to be against the idea because she is focused on her career as a fashion designer.
In March, Mel C dismissed speculation they would reunite for the Queen's Diamond Jubilee Concert: 'Not true. It was an honour to be asked (for the Jubilee concert), but not everyone is comfortable about doing it so we have to respect each other’s feelings about that.'
While not directly addressing the Spice Girls reunion speculation, Victoria said this year: 'I was never going to be the best singer and it wasn’t my passion.'
During their four years in the charts, they enjoyed nine No.1 singles and two No.1 albums in the UK, including one No.1 single and album in the U.S.