The next question: what will the bride wear?
The road to the engagement may have been protracted and stressful, but now comes the really hard part: finding the dress.
Kate Middleton's bridal gown is a dress that will go down in history. It will turn its designer into a global household name; it will set trends; and it will be seen by billions -- and preferably not on Twitter or Facebook before she walks down the aisle. But to whom will the 21st-century's "people's princess" entrust this most monumental of royal commissions?
First, it seems safe to assume she will fly the flag and choose a British designer. Second, Kate is very much her own woman and, given her strong-minded individuality, is unlikely to pick someone with royal "form", such as, for example, Samantha Shaw, who designed a bridal gown for the Countess of Wessex.
Third, Kate Middleton has never been one for obvious fashion choices. Her wardrobe, assured and appropriate as it may be, is selected from reliable brands such as Jigsaw, Kew, LK Bennett, Katherine Hooker and Issa. Wedding watchers support a classic, safe pair of hands, such as Stewart Parvin, who has a royal warrant, or Phillipa Lepley, who dresses top-tier Sloaney brides or Amanda Wakeley, who specialises in grand glamour.
Deborah Joseph, editor of 'Brides', suggests she might opt "for one of Diana's favourite designers such as Bruce Oldfield or Amanda Wakeley, "out of respect for William".
"Where the wedding is going to be held will, in some ways, denote the style and shape of the gown," said designer Lindka Cierach. "Diana was married in St Paul's, which is huge, so she needed a really big gown (the Emanuel design had 100 metres of silk in the petticoat alone), whereas Sarah Ferguson was married in Westminster Abbey, which is smaller.
"It is important to remember that every stitch, every seam, every bead will be under scrutiny." (© Daily Telegraph, London)