LONDON (AP) — She played a memorable supporting role at sister Kate’s 2011 royal wedding, but Pippa Middleton will take center stage Saturday at what looks to be Britain’s high society event of the year.

The 33-year-old is marrying a wealthy financier at the oh-so-English 12th-century church of St. Mark’s in the village of Englefield, west of London — with a guest list of young A-list royals and reality TV stars looking on.

Prince William, a future king, will be there with his wife Kate, now formally known as the Duchess of Cambridge, and their two children, Prince George, 3, and 2-year-old Princess Charlotte.

If that isn’t enough to merit a few photographs, there is widespread speculation that Prince Harry will bring his girlfriend, American actress Meghan Markle, to showcase their budding romance.

Here’s what to look for at the almost-royal wedding that is kicking off England’s summer social season in style:

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WHO IS SHE MARRYING?

The groom is hedge fund manager James Matthews, who proposed last summer during a trip to England’s scenic Lake District.

They had dated for less than a year — although the couple had briefly been an item in 2012 as well — when he got down on one knee and asked her to marry him.

The wealthy Matthews has shunned the spotlight, but his brother Spencer Matthews has surely compensated for that and more with his role on the reality TV show “Made in Chelsea.” He is expected to be the best man.

British bookmakers are taking bets on whether Spencer Matthews will be removed from the ceremony, perhaps for making an off-color speech. Paddy Power is offering 33/1 odds against that happening.

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WHAT ROLES FOR PRINCE GEORGE AND PRINCESS CHARLOTTE?

Prince George will be a page boy and Charlotte — at the tender age of 2 — will be a bridesmaid.

It goes without saying that whatever outfits their parents come up with will be closely monitored and copied by parents with young children for years to come.

Less clear is what will happen if George or Charlotte decides it’s tantrum-time.

Their mother told a palace guest this week that she is hoping for the best but admitted she’s a bit concerned her children may act up. Her husband, Prince William, is still being ribbed for his poor behavior — he stuck out his tongue at one point — at his Uncle Andrew’s wedding in 1986, when William was just 4.

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DOES THE QUEEN HAVE A ROLE?

Palace officials say Queen Elizabeth II will not be at the wedding. Prince Charles and his wife Camilla also plan to miss the event, which is drawing only the younger royals.

It was not known if they were invited or not.

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WILL PRINCE HARRY BRING HIS AMERICAN GIRLFRIEND?

Suspense is building over whether Prince Harry will use the occasion to spotlight his relationship with American actress Meghan Markle, who plays an ambitious paralegal in the U.S. television drama “Suits.”

Though they have only rarely gone out in public together, Harry has made his feelings for Markle known. In November he released an unusual letter calling for the press to stop intruding into her private life and saying he would do everything possible to protect her from unwanted scrutiny.

Escorting Markle to such a high-profile event would be seen as confirmation that the relationship is increasingly serious. Some expect Harry to attend the church ceremony solo then bring Markle to the reception.

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WHAT WILL PIPPA WEAR?

She looked terrific in a form-fitting Alexander McQueen dress at Kate’s 2011 wedding but is likely to wear something more modest at her own.

A number of British-based designers are thought to be likely contenders for one of the most highly anticipated commissions of the year, including Jenny Packham, Erdem, Giles Deacon and Philippa Lepley. Middleton is expected to wear a traditional, embroidered gown, most likely with the spectacular beadwork and detailing that mark high-end British fashion.

Hatmaker to the stars Stephen Jones — also known for his veils — may also be involved.

The bride is then expected to change into something jazzier for the reception, which is being held at her parents’ country estate in Bucklebury, 50 miles (80 kilometers) west of London.