By Mia O’Hare Simon Cowell’s fiancée Lauren Silverman looked gorgeous as she attended a charity bash alongside royalty and A-listers. The socialite, who shares son Eric with the music mogul, wowed in a black gown at the Air Ambulance gala held at Raffles in London. She paired the floor-length dress with strappy black heels and gold hooped earrings. Lauren wore her luscious black hair down and swept over one shoulder. The mum-of-two beamed as she posed for photos with her friend at the star-studded event. Lauren and the Britain’s Got Talent judge have been together since 2013. They welcomed the…