'No one could find the document' Kate Middleton's family may have lost one of her most important pieces of work

Kate Middleton has revealed at an official event that her family may have lost one of her most important pieces of work.

If you can count on someone to keep and treasure your school work (including those not-so-great old drawings) it's usually your parents - but maybe not in the Middleton household.

During a visit to the National Portrait Gallery - of which she's been a patron of since 2012 - the Duchess of Cambridge revealed that mum Carole and dad Michael lost a piece of work that was very important to her.

The mum-of-two made the revelation while touring an art exhibition of Victorian photography - Victorian Giants: The Birth Of Art Photography. As an history of art graduate, Kate wrote several captions for the images at the exhibition.

In a foreword to the exhibition, she wrote: 'This period in the history of photography has long interested me.

Kate at the National Portrait Gallery

'As a student at the University of St Andrews, I chose it as the subject of my undergraduate thesis and photographs of children in particular, which feature predominantly within the exhibition, are of real interest to me.'

But as it turns out, her undergraduate thesis is nowhere to be found. Speaking to the exhibition curator Dr Phillip Prodge, Kate explained how it somehow got lost in the family paperwork.

He said: 'She was very self deprecating about that, and she did explain to me that somewhere in her family archives she has stashed away her undergraduate thesis, and there was a moment when she asked her family if she couldn't retrieve it, but no one could find the document.'

The mum helped write captions for the photographs displayed at the exhibition

In the forward for the exhibition, Kate also opened up on motherhood, saying that children's 'boundless potential' should be celebrated, and that that it's what underpins her role as a mother to Prince George and Princess Charlotte, and the child she's currently expecting.

'These photographs allow us to reflect on the importance of preserving and appreciating childhood while it lasts.

'Children held a special place in the Victorian imagination and were celebrated for their seemingly boundless potential.

'This notion still rings true for us today and it underpins much of my official work and the charities I have chosen to support, and, indeed, my role as a mother of a young family.'

Have you ever lost one of your children's important pieces of work? Do you keep everything? Let us know in the comments!