Millie Mackintosh and Professor Green make their first public appearance after engagement

They announced their engagement to the world via Twitter and Instagram.

And last night Millie Mackintosh and Professor Green stepped out together for the first time since sharing their happy news.

The couple were among guests attending Esquire's Big Black Book launch party at Sushi Samba in the Heron Tower.

The 23-year-old Made in Chelsea star was keen to show off her engagement ring to other guests as she stood alongside the 29-year-old rapper.

The couple - who started dating in December 2011 - announced their engagement yesterday.

Along with posting a photo of her ring, Mackintosh wrote: "If I could scream loud enough for the whole world to hear I would."

And her new fiancé - whose real name is Stephen Manderson - also commented on the news with a tweet to his followers, joking people need to tell other celebrities he is off the market.

He said: "Happy days. Someone's gonna have to break the news to Jessica Alba and Eva Mendez."