The Queen's eldest grandson, Peter Phillips will marry his fiancee Autumn Kelly at Windsor Castle.Mr Phillips, the 11th in line to the throne and son of the Princess Royal, met his Canadian bride-to-be in 2003 at the Montreal Grand Prix where they were both working.The couple, who are both 30, will exchange vows at the chapel and will then host a reception and dance at Frogmore House, Windsor, which has been lent to them by the Queen and Duke of Edinburgh.Although the ceremony is likely to see a large royal turnout one notable absentee will be Prince William who is said to be attending a wedding of a close friend in Africa.Kate Middleton is expected to attend Mr Phillips' wedding in his place and her presence at the ceremony has been hailed as a clear signal that she has been fully accepted into the Royal Family.Prince Harry's girlfriend Chelsy Davy is also reported to be attending the wedding in Windsor where she will be formally introduced to the Queen for the first time.The ceremony is likely to see the largest royal turnout in several years and many senior members of the family have confirmed they will be in attendance.The Prince of Wales and the Duchess of Cornwall, Prince Harry and the Duke of Edinburgh are all expected to be part of the wedding party.The bride, Miss Kelly, was a former Roman Catholic and has only recently been accepted into the Church of England.If she had not changed churches, Mr Phillips would have had to give up his right to become king.