Friends including Jessica Mulroney, Misha Noo Lindsay Roth, Benita Litt, Janina Gavankar and Priyanka Chopra are expected to be part of the congregation. Prince Harry went on to tease his brother mercilessly during a none-the-less heartfelt best man’s speech at the wedding reception, allegedly wearing a fez, mimicking the lovestruck conversations between a young Kate and William, and ridiculing his bald spot.Royal men have traditionally had “supporters” by their side at their wedding, with both Prince William and Prince Harry now breaking with the convention to use the more modern term of “best man”. The pair were cheered by the crowds as they arrivedCredit:PA The Duke, who has always been the front-runner for the supporting role at the May wedding, is “honoured” to have been asked, Kensington Palace said. Asked how he felt about being asked to be Prince Harry’s best man, the Duke said: “It feels great. [I am] Thrilled and delighted obviously. Earlier this year, the Duke talked of the lifelong close bond he has enjoyed with his brother, saying at a charity event about male mental health in January: “Our relationship is closer than it’s been because of the situation we’ve been through.”Losing our mother at a young age, it’s helped us travel through that difficult patch together. You’re like-minded.”You go through similar things, it’s a bond and it’s something you know you’ve tackled together and come out better for it.”After the ceremony inside the chapel, which is in the grounds of Windsor Castle, he is expected to deliver a traditional best man’s speech. Jessica Mulroney and Meghan Markle in 2016Credit:George Pimentel/WireImage Prince William and Prince Harry in borrowed policemen outfitsCredit:PA The best man and bridesmaidsThe Duke of Cambridge will be Harry’s best man, missing the FA Cup final to be at his brother’s side. The two spent the night at the Dorchester Collection’s Coworth Park where the cheapest room available costs £370.Meghan Markle stayed at a hotel 15 miles away – the Cliveden House Hotel – with her mother Doria Ragland. Prince Harry was Prince William’s best man in 2011 when the Duke and Duchess of Cambridge wed inside Westminster Abbey. Prince George and Princess Charlotte were almost certain to be page boy and flower girl. The siblings already know the score – they performed those roles at the wedding of Pippa Middleton, the Duchess of Cambridge’s younger sister, to James Matthews in May last year. Kensington Palace has announced that Ms Markle will have no adult bridesmaids ‘because she’s unable to choose between her friends’, and will instead be surrounded by children as page boys, bridesmaids and flower girls. “Revenge is sweet. I’ll be looking forward to it.”The Duke’s own stag do is reported to have been held on a Devon estate, Hartland Abbey, where he and close friends indulged in drinking, clay pigeon shooting, surfing and games. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. FOLLOW LIVE COVERAGE OF THE ROYAL WEDDING HEREThe Duke of Cambridge arrived with Prince Harry at St George’s Chapel, taking up his role as best man for his brother at the Royal Wedding – and returning the gesture from his own big day seven years ago.Both Harry and the Duke of Cambridge wore the frockcoat uniform of the Blues and Royals.The Queen gave her permission for her grandson to get married in his uniform, Kensington Palace said. Both uniforms were tailored at Dege & Skinner on Savile Row.Prince Harry and the Duke looked relaxed as he walked down to the chapel with his brother, the Duke of Cambridge, to loud cheers from the waiting crowd.The pair smiled and waved to well-wishers during the short walk.