Prince Harry and Meghan Markle will likely have half as many guests as Prince William and Duchess Catherine at their wedding.

Prince Harry and Meghan Markle

Prince Harry and Meghan Markle

Royal expert Alastair Bruce has said that there is less "pressure" on the 33-year-old royal to invite extended members of the royal family because he's not a "direct line of succession" like his elder brother, The Duke of Cambridge.

However, he added that it is up to the couple themselves how many people they'd like to attend their forthcoming nuptials at St George's Chapel at Windsor Castle, which can hold up to 800 guests.

Bruce told Town and Country magazine: "It's very much a matter for the bride and the groom.

The thing about Prince Harry is that he's not seen to be in the direct line of succession, and therefore the pressure on him to invite the long list of people, who had to be asked to the wedding of the Duke and Duchess of Cambridge, is not present."

Meanwhile, as their plans get underway, Prince William recently admitted Harry is yet to ask him to be his best man.

The 35-year-old prince is expected to take on the role at his brother's wedding to Meghan Markle on May 19 but the flame-haired royal is clearly making his sibling wait to find out, and William joked it "could be a sensitive subject".

He said: "He hasn't asked me yet, just to clear that up. It could be a sensitive subject."

William also admitted he is "trying to see what I can do" about being able to attend the FA Cup final in his role of President of the FA on the same date as his brother's nuptials, when asked by former England star Rio Ferdinand if he will be able to go.

He made the revelation as he joined staff, volunteers, and supporters of charity CALM (Campaign Against Living Miserably) for a group discussion about their new Best Man Project initiative, to promote the idea men shouldn't wait until a wedding to prove they are a great friend.