A major wardrobe malfunction left Lily Allen's brother in tears when he met Princess Diana.

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Lily Allen’s new memoir My Thoughts Exactly has become a never-ending source of juicy stories from behind the curtain of British aristocracy.

Like the time the 33-year-old singer and her Game of Thrones actor brother Alfie Allen were lucky enough to meet the late Princess Diana of Wales.

It was a tale that had all the makings of an adorably cute family moment, caught on VHS for the whole family to re-watch at Christmas until eternity.

Sadly, an unfortunate wardrobe malfunction made the encounter with royalty memorable for all the wrong reasons.

Picture this:

Lily and her brother, six and five at the time, were being very good by helping out their parents at the 1992 London premiere of Hear My Song, a film produced by their mother.

The kids, dressed up in cute wedding-like outfits, were given the very important task of greeting a then-31-year-old Princess Diana with gifts.

This is where things went horribly wrong.

In her book, Lily wrote that Alfie found himself negotiating a painful wardrobe malfunction moments before shaking the Princess' hand.

"Diana the Princess of Wales came to the premiere. I was a flower girl and gave her a posy, Alfie had a box of handkerchiefs to give her but somehow he got his k*** caught in his trouser zip moments before meeting her," the book reads, Daily Mail reports.

When Princess Diana approached the children and saw Alfie crying, understandably, she asked the small boy what was wrong.

“He was crying when she approached him,” Lily wrote.

“’Are you OK?’ she asked him. ’No,’ he replied. ‘I’ve got my willy caught in my zip.’”

Considering she was a mother of two young boys at the time, there's no doubt Princess Diana would've known exactly what to do to make Alfie smile.

The meeting happened in 1992, just five years before Princess Diana's tragic death when she and her partner Dodi al Fayed were killed in a Paris car crash in 1997.

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