Kate MiddletonandPrince Williamshared news of their engagement with the worldnine years ago this week — and Kate included a special nod to their relationship during theirdate nighton Monday.

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Catherine Duchess of Cambridge and Prince William at The Royal Variety Performance, Arrivals, London Palladium, UK - 18 Nov 2019

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Britain’s Prince William and his wife Ka

Catherine Duchess of Cambridge and Prince William at The Royal Variety Performance, Arrivals, London Palladium, UK - 18 Nov 2019

Kate accessorized her look for the Royal Variety Performance with dangling Erdem earrings, which she previously wore when she officially opened the new Photography Centre at the V&A last October, and a black velvet clutch. The finishing touch was her signature bouncy blowout.

Meanwhile,Prince William— who has been taking a number offashion riskslately! — kept it classic in a black tuxedo and bow tie.

Kate Middleton.Karwai Tang/WireImage

Britain’s Prince William, Duke of Cambridge (2nd L) and Britain’s Catherine, Duchess of Cambridge (2nd R) sing the national Anthem in the Royal Box as they attend the Royal Variety Performance at the Palladium Theatre in central London on November 18, 2019

Kate Middleton and Prince William.Neil Mockford/GC Images

Catherine Duchess of Cambridge and Prince William at The Royal Variety Performance, Arrivals, London Palladium, UK - 18 Nov 2019

The duo even showed off a rare moment of PDA — William affectionately put his hand on Kate’s back as the entered the event.

Prince William and Kate Middleton.BACKGRID

Prince William and Catherine Duchess of Cambridge - Kate Middleton pictured arriving at the Royal Variety Performance at the London Palladium in London

William and Kate, both 37, met with some of the performers and charity members before and after the show.

Catherine Duchess of Cambridge and Prince William at The Royal Variety Performance, Arrivals, London Palladium, UK - 18 Nov 2019

GEOFF PUGH/POOL/AFP via Getty

Britain’s Prince William, Duke of Cambridge (2nd L) and Britain’s Catherine, Duchess of Cambridge (2nd R) sing the national Anthem in the Royal Box as they attend the Royal Variety Performance at the Palladium Theatre in central London on November 18, 2019

Last year,Meghan Markle and Prince Harry attended the eventon behalf of the royal family. But they are currently on asix-week break from their royal dutiesto spend some valuable “family time” together, a royal source confirmed to PEOPLE.

The origins of the Royal Variety Performance date back to 1912 when King George V and Queen Mary agreed to attend a “Royal Command Performance” at the Palace Theatre in London, in aid of the Variety Artistes’ Benevolent Fund. In July 1919, the second royal show was performed and was the first to be billed a “Royal Variety Performance.”

Prince William and Kate Middleton.GEOFF PUGH/POOL/AFP via Getty

Britain’s Prince William, Duke of Cambridge (2nd L) and Britain’s Catherine, Duchess of Cambridge (2nd R) sing the national Anthem in the Royal Box as they attend the Royal Variety Performance at the Palladium Theatre in central London on November 18, 2019

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source: people.com