Prince Harry's military uniform was noticeably different from his brother's, Prince William, and uncle's, Prince Andrew, as they each stood vigil over Queen Elizabeth II's coffin at Westminster Hall ahead of her funeral on Monday.
The "ER" initials were positioned on the shoulder of Prince William's uniform and were also seen on Prince Andrew's military regalia during another senior royal vigil. The initials stand for "Elizabeth Regina" in Latin.
Prince Harry was finally allowed to wear his military uniform at the last minute after receiving approval from King Charles III, when Kensington Palace announced the surprise, 15-minute vigil with the queen's grandchildren on Friday.
"We do not know why the initials were removed from Prince Harry's uniform, but I am told that Prince Harry was so distraught over the removal that he seriously contemplated not wearing his uniform during the vigil," royal expert Kinsey Schofield exclusively told Fox News Digital.
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The Duke of Sussex, who served 10 years in the British Army, wore a Blues and Royals No. 1 Uniform, KCVO Neck Order and Star, Afghanistan Operational Service Medal, Golden, Diamond and Platinum Jubilee medals and Army Pilot Wings.
Schofield added, "I'm told he almost wore his morning dress instead. I don't think instances like this are a personal attack on him, but unfortunately he believes that they are."
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Harry and wife Meghan Markle had departed from royal duties and moved to the United States due to what they described as the British media's intrusion and racist demeanor toward their family.
Prince Harry not wearing the "ER" initials could simply be a royal mishap.
"It could be an oversight," Duncan Larcombe, Fox News contributor, said. "It makes no sense."
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The "oversight" is even more questionable given that Prince Andrew, who was stripped of his royal titles and patronages in 2022, was seen wearing the insignia.
Andrew is no longer a senior working royal following the unfolding of his friendship with late sex offender Jeffrey Epstein. The prince was then accused of sexual assault by Virginia Giuffre and was banned from using the "HRH" titles.
Despite the announcement made that only working members of the royal family would be allowed to wear military uniforms, an exception was made Friday night for the Duke of York as he stood vigil alongside King Charles III, Princess Anne and Prince Edward with the King's Body Guard to protect Her Majesty's coffin.
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In attendance at Saturday's special vigil were Princess Anne's children, Zara Tindall and Peter Phillips; Prince Andrew's daughters, Princess Beatrice and Princess Eugenie; and the children of Prince Edward, Lady Louise Windsor and James, Viscount Severn.
"I am glad the king thought better of it," Shannon Felton Spence told Fox News Digital. "It's the right thing to do. The queen was immensely proud of Prince Harry's service as his granny and as his commander-in-chief."
Buckingham Palace is otherwise only allowing current working members of the family with military titles to wear uniforms at the funeral.
Two minutes of silence will be observed at the end of Her Majesty's funeral Monday, giving the British public a chance to pay their final respects to the late monarch.
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Fox News' Caroline Thayer contributed to this report.