Harry, 33, and his American fiancee, 36, have not said where they will hold the ceremony but if they choose the UK most senior royals marry at Westminster Abbey, St Paul's Cathedral or the chapel at Windsor Castle.
They have chosen to state they are getting married just before they spend their first proper Christmas together.
Meghan, who is divorced, could become a princess or alternatively be given the title Duchess of Sussex when she marries the fifth in line to the throne and joins the royal family.
But they are likely to wait until Prince William and Kate have their third child, which is due in April.
Bookmakers refused to take any more bets on the couple getting engaged last week as Meghan landed in London and started moving her belongings and two dogs to the UK.
Social media went into meltdown but they have had to wait until today to hear that the fifth-in-line to the throne has proposed to his actress girlfriend.
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