William, 35, is “honoured” to have been chosen by his younger brother to perform the special role, and the Scottish Highlands is tipped to be their choice for a stag party. Harry’s decision was widely expected as the royal siblings are very close and he served as William’s best man during his 2011 wedding to the Duchess of Cambridge.
Underneath the public banter, where they regularly poke fun at each other, the pair share a special bond which was strengthened following the death of their mother Diana, Princess of Wales, in a Paris car crash.
William spoke about their connection during 2017 - the 20th anniversary year of Diana’s death - telling Kate during an interview, as Harry, 33, sat with them: “We have been brought closer because of the circumstances as well that’s the thing. You know, we are uniquely bonded because of what we’ve been through.”
The Prince of Wales also chose his brother the Duke of York to be his main supporter - a royal alternative to best man - when he married Lady Diana Spencer at St Paul’s Cathedral in 1981.
Kensington Palace said: “The Duke of Cambridge is honoured to have been asked, and is very much looking forward to supporting his brother at St George’s Chapel, Windsor on May 19.”
The palace has issued a series of tweets with pictures to mark the announcement including an image of the royal brothers as young boys dressed up as mock policeman.
On the wedding day the duke is likely to be tasked with looking after Meghan’s wedding ring and is expected to give the traditional best man’s speech at the private evening event being staged by Charles at Frogmore House.
The Highlands is one of the top choices with bookies as a stag-do destination.
The royals know it well and it will give them the privacy to indulge in outdoor pursuits and keep their antics under wraps.
Rupert Adams from William Hill said: “Prince William has been confirmed as the best man, and we think that has increased the chances of a trip to Scotland, which is now 5-2 from 8-1, although Switzerland is the favourite at 6-4.”
Las Vegas - where Harry was photographed partying naked in 2012 - is a 100-1 shot with Ladbrokes as a stag-do destination, but a more realistic choice for William is their 5-1 favourite, the Scottish highlands, or a private hideaway in Wales fancied at 8-1.
London has odds of 20-1 with the royals, and their pals, possibly partying away at one of the haunts of good friend Guy Pelly.
Jessica Bridge of Ladbrokes said: “Prince Harry’s days in Las Vegas are over, and despite it being his last night of freedom, it looks safe to say he’ll be keeping the bash low key in the UK.”