Royal Wedding: Everything to know before Prince Harry marries Meghan Markle

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LONDON — On May 19, Prince Harry and Meghan Markle will marry in Windsor, England, in a ceremony that will be low-key only by royal standards.

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Rachel Meghan Markle of California (aka "Meghan"), 36, is the only child of Thomas Markle and Doria Ragland, who are divorced. She co-starred for seven seasons on "Suits" on USA Network, but says she's retired from acting (one day after the royal engagement announcement on Nov. 27, USA made it official Markle wouldn't be back for season eight.) Her last appearance, in the two-hour season finale, aired April 25.

The happy couple:

Prince Henry Charles Albert David of Wales (aka "Harry"), 33, is the grandson of Queen Elizabeth II and the younger son of Prince Charles and the late Diana, Princess of Wales. He's fifth in line to the throne (Charles is first), but will slip down another rung any day now when his sister-in-law Kate, the Duchess of Cambridge, gives birth to her third child.

The reception: All guests invited to the actual ceremony will attend a luncheon afterward hosted by the queen at St. George's Hall. The traditional wedding cake for royal weddings is fruitcake.

But Harry and Meghan are said to be going rogue and having a "lemon elderflower cake" with buttercream icing. Next up: A reception that night for an even more select guest list of 200 people that Prince Charles is throwing at Frogmore House, another royal residence about a half-mile from Windsor Castle.

The wedding party: The Brits do this differently, generally favoring little kids as "bridesmaids"/flower girls and page boys instead of adult attendants. In past royal weddings this has led to such memorable incidents as a wee Prince William playing with his straw boater hat and chattering away during the 1986 nuptials of Prince Andrew and Sarah Ferguson. Right now, William's own kids, Prince George and Princess Charlotte are considered locks for Uncle Harry's wedding party; so is the 4-year-old daughter of Markle's Canadian stylist and close friend, Jessica Mulroney. Meanwhile, you can bet on everything in the U.K.when it comes to this wedding and William is getting top odds to be his brother's best man (oddsmaker William Hill also is taking bets on how William will wear his hair on the big day).

On April 26, Kensington Palace sent out a tweet making it official that William will be Harry's best man.

Who's invited: Six hundred invitations to the ceremony have gone out (the chapel seats about 800). Count on all the immediate royal relations (The Queen and Prince Philip, Uncle Prince Andrew and his fun loving daughters Beatrice and Eugenie), plus various dukes and duchesses and major and minor European royalty.

Then there are some celebrity friends of the bride -- tennis star Serena Williams) and groom -- singers James Blunt and, if you believe the tabloids, Rihanna -- who should make the cut. Also, the Spice Girls may or may not be there. Mel B, aka Scary Spice, has said they will be, but when asked about it by "Late Late Show" host James Corden, Posh Spice Victoria Beckham  stammered, "I don't know."

What about Fergie? That would be Sarah Ferguson, the Duchess of York and friend of Harry's late mother, Diana. The fun-loving redhead fell out of favor with the royal family after her 1996 divorce from Prince Andrew. In a very public dis, she was left off the guest list for William and Kate's 2011 wedding.

British tabloid the Sun quoted an unnamed source who said she won't be there because Harry supposedly couldn't trust her to "keep her mouth shut and respect their privacy." People reported Harry had "pushed for" Fergie to be invited because he's very close to her daughters, Princesses Eugenie and Beatrice.

What about Meghan's family? Though long divorced, Markle's parents released a joint statement of joy over her engagement and it's said both will be at the wedding. In fact, Thomas Markle, an Emmy-winning lighting director, is expected to give his daughter away.

After that, things get a bit sticky. Proving that the royals don't have a monopoly on family issues, Meghan's two older half siblings from her dad's first marriage reportedly aren't invited -- and at least one of them isn't happy about it. Her half sister, Samantha Grant, has reportedly claimed Meghan is "inviting 2000 complete strangers" to the wedding rather than family and even blasted Harry about it with a "Time to man up!" tweet. Grant's reportedly writing a book about Markle. Trevor Engelson, an American movie and TV producer and Markle's ex-husband, is said by some British newspapers to be developing a show about an American divorcee who moves to England to marry a prince.

Meghan's wedding dress: Despite her convention-flouting penchant for wearing pants at some royal engagements, it's expected that Markle will wear a dress. The design is top-secret, but the designers mentioned most often as front-runners to create it are Erdem Moralioglu, Ralph & Russo and Alexander McQueen. All three are London-based and McQueen designed Kate Middleton's royal wedding gown. With it being the U.K., spectators can bet on the dress. However, sometimes British bookmakers have periodically suspended betting as a lot of money pours in on one particular designer.

Royal Wedding souvenirs : Shops in London already have royal wedding mugs, tea towels, decorative objects and the like for sale.