Princess Beatrice has the sweetest reaction to Karlie Kloss's engagement

Supermodel Karlie Kloss has accidentally revealed the secret Instagram account of Princess Beatrice.

The blunder happened moments after Kloss announced her engagement to tech entrepreneur Joshua Kushner.

He's the brother of Jared Kushner, who is married to Ivanka Trump – making him Donald Trump's son-in-law.

Kloss, 25, gushed over her new fiancé on Instagram, writing, "I love you more than I have words to express. Josh, you’re my best friend and my soulmate. I can’t wait for forever together. Yes a million times over 💍".

She then flashed her engagement ring in a video shared via Instagram stories, along with the caption, "My phone is blowing up with the sweetest messages from loved ones. This poor makeup artist is gonna kill me".

The video included reactions from friends and family, including Princess Beatrice of York.

Her reaction was quite possibly the sweetest – it was a photo of the young royal looking very shocked.

However, in the process of sharing the reaction, Kloss revealed Beatrice's private Instagram handle @beayork.

The account allows only approved followers to see posts by the Princess.

Beatrice, 29, is the eldest daughter of Prince Andrew, the Duke of York, and Sarah Ferguson.

She has been friends with Kloss, a former Victoria's Secret Angel, for many years.

In 2016, Kloss and the Queen's granddaughter attended a wedding together on the French Riviera and even went on holidays to Jordan, in April, along with pop star Ellie Goulding.

Princess Eugenie has a busy year ahead – in October she'll be attending the wedding of her sister, Princess Eugenie to fiancé Jack Brooksbank, and it's highly likely she'll also be helping to organise the coming nuptials of Kloss and Kushner.