PRINCE Harry is to marry his American actress girlfriend Meghan Markle, Clarence House has announced.

The Queen and Duke of Edinburgh "are delighted for the couple and wish them every happiness", a Buckingham Palace spokesman said.

Meghan Markle's parents Thomas Markle and Doria Ragland have said they are "incredibly happy" with the couple's engagement, adding: "We wish them a lifetime of happiness."

The engagement poignantly comes in the year that marked the 20th anniversary of his mother's death.

Diana, Princess of Wales was tragically killed in a Paris car crash in 1997 when Harry was just 12-years old.

Here is the announcement of Prince Harry and Meghan Markle's engagement

HIS ROYAL HIGHNESS PRINCE HENRY OF WALES AND MS. MEGHAN MARKLE ARE ENGAGED TO BE MARRIED His Royal Highness The Prince of Wales is delighted to announce the engagement of Prince Harry to Ms. Meghan Markle.

The wedding will take place in Spring 2018. Further details about the wedding day will be announced in due course.

His Royal Highness and Ms. Markle became engaged in London earlier this month. Prince Harry has informed Her Majesty The Queen and other close members of his family. Prince Harry has also sought and received the blessing of Ms. Markle's parents.

The couple will live in Nottingham Cottage at Kensington Palace.

What happens next?

Prince Harry is engaged to be married to Meghan Markle and a royal wedding is being planned. So what happens next?

OFFICIAL PHOTOCALL The prince and his bride-to-be will be expected to show off the engagement ring as they pose for their first photographs since announcing their impending nuptials.

The Duke and Duchess of Cambridge appeared together the same day at St James's Palace in 2010, with Kate wearing the sapphire and diamond engagement ring that belonged to William's mother, Diana, Princess of Wales.

There will also probably be a pre-recorded television interview and at a later date a set of official engagement photographs.

William and Kate's were taken by celebrity photographer Mario Testino.

SETTING A DATE A date will have already been fixed. Royal aides are said to have synced royal diaries a while ago to find a suitable day and make sure the Queen, the Prince of Wales and the Duke and Duchess of Cambridge and other royals could all attend.

Royal weddings usually take place only a few months after an engagement announcement.

March is the most likely month, leaving enough time to ensure pregnant Kate is not about to give birth to her third child.

VENUE The venue will also have been decided and the Archbishop of Canterbury is expected to perform the ceremony.

St George's Chapel at Windsor Castle is a good bet. The 15th century church is grand, but will allow for a smaller scale royal wedding compared with Westminster Abbey and St Paul's Cathedral.

SECURITY The Metropolitan Police will start planning immediately for the high-profile event. The current threat level for international terrorism in the UK is severe.

Extra officers will be drafted in to patrol the streets on the day amid tight security surrounding the chosen venue.

Ms Markle will also have been assigned a royal bodyguard from the Metropolitan Police's Royalty and Specialist Protection Command.

THE GOWN Bridal-wear designers around the world will be hoping to get the call for this royal wedding.

Ms Markle will no doubt already have an idea of what she wants.

The actress appeared in an Anne Barge ballgown wedding dress for her role as Rachel Zane in Suits, and her own first wedding to TV producer Trevor Engleson saw her wear a sleek, strapless, floor-length white dress with diamante detail.

Her stylist and close friend Jessica Mulroney runs the bridal store Kleinfeld Hudson's Bay in Toronto, so it is likely Ms Mulroney will be Ms Markle's first port of call for help picking out dress amid great secrecy.

GUESTS Harry and his fiancee will have already drawn up a guest list, but there will also be a number of dignitaries they have to invite.

The prince's grandmother, the Queen will, however, be on hand to help.

William revealed after his 2011 wedding: "I went to (the Queen) and said 'Listen, I've got this list, not one person I know. What do I do?'