Royal wedding: Guests and supporters descend on Windsor for Harry and Meghan's big day

Thousands of well-wishers from around the globe have descended on Windsor as the wedding of Prince Harry and American actress Meghan Markle approaches.

The couple will become the Duke and Duchess of Sussex after the Queen bestowed the title on her grandson hours before the service was set to take place.

Harry also received Scottish and Northern Irish titles, becoming the Earl of Dumbarton and Baron Kilkeel, which means Meghan will become the Countess of Dumbarton and Baroness Kilkeel.

Royal fans have flooded the Berkshire town to catch a glimpse of the bride and groom, as police have effectively created a ring of steel around the castle in a massive security operation.

It was the fourth night camping out on the street for Canadian Bernadette Christie, who says the waiting will have all been worth it if she sees the royal couple pass by in their state carriage.

“I’m freezing cold, my back is sore, and I just want to go to bed,” she said.

“I’m here for that 10 seconds when the coach comes around the corner.”

The service itself will begin at noon in the 15th Century St George's Chapel in Windsor Castle and will be led by the Dean of Windsor, David Conner, while the Archbishop of Canterbury Justin Welby will solemnise the marriage.

Ms Markle, who attended a Roman Catholic school, has been baptised into the Church of England, of which the Queen is supreme governor.

In a break from tradition, Bishop Michael Curry, head of the US Episcopal Church, will also deliver a sermon during the proceedings.

The first black leader of the Anglican organisation, Chicago-born Bishop Curry has forged a reputation for his progressive stance on issues such as same-sex marriage, while his sermons often focus on social justice.

“The love that has brought and will bind Prince Harry and Ms Meghan Markle together has its source and origin in God, and is the key to life and happiness,” the bishop said in a statement.

The world's media has been gripped by the union of Harry, 33, sixth-in-line to the British throne, and Ms Markle, 36, a divorcee whose mother is African American and father is white.

To some black Britons, the wedding marks a breakdown of barriers and reveals a more modern Britain, while to others it is an irrelevance, with polls suggesting the majority of the nation will not tune in on television.

The bride will arrive at the church with her mother, Doria Ragland, 61, with whom she spent Friday night at a luxury hotel.

Harry was staying at another hotel with elder brother and best man Prince William, whose daughter Charlotte and son George will be among the bridesmaids and page boys.

In a walk that will lead her into one of the world's grandest royal families, Ms Markle will enter the chapel unescorted, with her bridesmaids and page boys.

Halfway down the aisle she well be joined by heir-to-the-throne Prince Charles, who will lead her to the altar where his son, Harry, waits.

Her own father Thomas Markle, 73, pulled out of taking part in the ceremony this week after revealing he had undergone heart surgery on Wednesday.

Mr Markle had become mired in a scandal last week surrounding claims he worked with paparazzi to stage photographs in exchange for money.

In a sign of modernity for the royals, Harry will wear a ring, while Ms Markle will not vow to obey her husband. Senior male British royals do not traditionally wear rings.

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 Frogmore House, another grand mansion in the grounds.

The prince and his new wife are not immediately leaving on honeymoon and will carry out their first official engagement as husband and wife next week.

Additional reporting by Reuters