The handsome pair met Louis Walsh and other friends just one day after they returned from their holiday together in the French Riviera, where the mum-to-be had reunited with X Factor judge Simon for the first time since the news of her pregnancy broke.
Simon, 53, looked delighted to be by Lauren's side on Wednesday evening. The New York socialite is thought to be around 13 weeks pregnant with his first child.
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The music mogul proudly posed alongside the 36-year-old in an open white shirt and jeans, smiling broadly before kissing her affectionately outside the quaint Italian restaurant, Scalini.
Lauren, meanwhile, was pretty in pink, showing off her blossoming baby bump in a knee-length dress with white high-heeled sandals. She held a cream clutch in one hand and a magazine in the other, with none other than Simon on the front cover.
Their first official outing comes after their pair spent a romantic few days in the south of France, where they met for the first time since the divorce to her husband of ten years was finalised last week.
Rather than return to Simon's luxury slipstream yacht, moored nearby, the couple stayed in a rented villa together.
"At her stage of pregnancy, it's little wonder she may want to be on dry land instead of sea," a source told the Mirror.
Before jetting off to spend quality time with his pregnant lover, Simon spoke for the first time about becoming a father.
On the red carpet at the One Direction movie premiere in London on Tuesday, the 53-year-old told Magic FM that he's "ready, excited and very happy" about the baby, calling Lauren " a lovely girl".
He went on to tell the BBC that he was "proud", adding, "Things are changing in my life right now, for the better.
"I'm proud to be a dad… It's something I hadn't thought of before, but now I know I feel good about it." The star added, "She's a very special girl."