NO VOW TO OBEY
Prime Minister Theresa May, who along with other politicians was not invited to the wedding, sent good wishes to the couple, adding: "To all of those joining the national celebration with street parties and other events, have a wonderful day."
In departures from royal custom, Harry will wear a ring - a platinum band - while Markle will not vow to obey her husband. Her wedding ring is made from Welsh gold, given by the queen.
In among traditional hymns, a choir will perform American soul singer Ben E. King's 1960s hit "Stand by me".
After the ceremony, the newlyweds are expected to greet some of the 1,200 members of the public invited into the castle grounds before starting a carriage procession through Windsor.
A reception will be held in the castle's St George's Hall before 200 guests join the couple at an evening event at the nearby Frogmore House mansion.
The newlyweds will carry out their first official engagement as husband and wife next week.
The British remain broadly supportive of the monarchy, albeit with a sense of mild irony about the pomp and pageantry that accompanies it, though most have deep respect for Queen Elizabeth after her 66 years of service as head of state.
Harry, along with brother William and his wife Kate, are at the forefront of efforts to modernise the monarchy by talking openly about their feelings.
"It is patently obvious - the more you say, the more you can be examined," said royal historian Hugo Vickers. "Everything moves on gradually - but there are certain risks, and there is a lot to be said for maintaining the mystique."
