Idris Elba and his fiancee Sabrina Dhowre and Oprah Winfrey trailing behind. Picture: Reuters

As Hollywood and British royalty are set to unite through the marriage of Prince Harry and American actress Meghan Markle the guest list, which excludes politicians will undoubtedly for made-up of the who's who and A-list celebrities.

Oprah Winfrey and Idris Elba are among the first guests to arrive at the royal wedding on Saturday

TV mogul Oprah was spotted arriving at St George's Chapel in Windsor Castle, Windsor just before 10am, while actor Idris Elba and his fiancee Sabrina Dhowre arrived at the same time as Oprah, making their way into the chapel almost two hours before the ceremony is due to begin.

Other celebrities reported to be on the guest list include George and Amal Clooney, David and Victoria Beckham, Priyanka Chopra and Meghan's former 'Suits' co-stars.

Guests in attendance are also required to wear hats, watch video below to learn why: