The unveiling of a statue to commemorate what would have been Princess Diana’s 60th birthday took place this week, with all eyes on the feuding royal brothers, Prince William and Prince Harry.

Now, a professional lip reader has revealed the ‘word of warning’ the Duke of Cambridge said to his younger brother.

Moments before the ceremony took place at Sunken Garden in Kensington Palace, lip reader Jeremy Freeman told the Daily Star, William gave a stern warning to Harry, telling him “I didn’t want anything to go wrong. It’s important we unveil it right.”

The pair commissioned the statue to honour their late mother four years ago, and appeared to stare fondly at it during the ceremony.

Over 4,000 flowers were planted in the princess’s favourite garden, taking 1,000 hours to complete.

The brothers haven’t been spotted together since the funeral of their great-grandfather, Prince Philip, in April.

John Cassidy, another lip reader told The Sun, the brothers appeared to be quite jovial in their exchange, claiming the older prince marvelled at the touching tribute, saying “Great isn’t it? Amazing little place.”

However, body language expert Judi James says the brothers united front appeared to be “overworked.”

“Emerging side-by-side their smiles did appear slightly over-worked at first but one very telling trait was how their body language was mirrored,” she told The Sun.

“This kind of mimicry suggests strong subliminal bonds, hinting that old ties still bind them despite their current rifts,” she continued.

During the ceremony, the brothers released a poignant statement, celebrating their mother’s legacy.

“Every day, we wish she were still with us, and our hope is that this statue will be seen forever as a symbol of her life and her legacy,” they said.

The statue will be open to the public to visit in line with Kensington Palace’s opening hours.

This article originally appeared on Over60.