Kate Middleton and Prince William joining Queen for TV special to air just before Meghan and Harry's tell-all with Oprah

Prince William and Kate Middleton will join Queen Elizabeth for a television special which will be broadcast just hours before Prince Harry and Meghan Markle's controversial interview with Oprah Winfrey. 

At least six of the senior members of the royal family will appear on British TV for A Celebration For Commonwealth Day, in which they will pay tribute to all the Commonwealth communities and their response to the COVID-19 pandemic. 

The timing of the broadcast, which will air on Sunday (UK time), means the Royal Family's message will be seen by millions of Brits before Harry and Meghan get to say their piece. 

Teaser clips for the Duke and Duchess of Sussex's unprecedented conversation with Oprah show Meghan hitting out at 'The Firm' - another name for the Royal Family - with a bombshell accusation that they are actively spreading lies about her and Harry. 

Harry and Meghan are expected to make more candid revelations about their reasons for stepping down from royal life during the two-hour-long special. 

The Commonwealth Day broadcast will see Kate and William speak to frontline healthcare, charity and volunteer workers to understand the work that has been carried out over the past year to keep people safe. 

The Queen, Prince Charles and Camilla will all also address the Commonwealth nations in pre-recorded messages. 

The Royal Family would usually attend a Commonwealth Day service on March 8 in person, however the event which is held at Westminster Abby was cancelled for the first time in nearly 50 years due to COVID-19. 

Instead, the Queen decided to schedule her annual message 24 hours earlier during the Celebration For Commonwealth Day broadcast. 

Last year's Commonwealth service took place just as Harry and Meghan had announced their intention to step down as working members of the royal family, and the event was the last time they were seen in public with Harry's grandmother, father and brother. 

CBS Presents Oprah with Meghan and Harry will air in Aotearoa exclusively on Three and online on ThreeNow at 7.30pm Tuesday, March 9.