Prince William and Kate Middleton say they're having a "difficult time" following Phillip's death

The Duke and Duchess of Cambridge, Prince William and Kate Middleton, have opened up about how their family is coping since the passing of their beloved grandfather, Prince Phillip. The Duke had been married to The Queen for 73 years at the time of his death and was 99 years of age.

Now, in a heart-warming thank you note sent to royal fan (who shared the letter on their blog, Gert's Royal Replies), Kate and William have sweetly responded to a message of condolence – and given an insight into how Philip's passing has impacted on their lives.

The Cambridge's revealed how they were privately dealing with the loss together as a family, saying, 'They will all miss their much loved grandfather and great-grandfather' but that messages of support have 'provided great comfort at this difficult time.'

Typically, royal correspondence features a photo of the couple or the entire Cambridge clan on the front of the card, whereas this reply was more muted and formal, simply featuring the Cambridge's monogrammed initials 'W & C' due to the sombre nature of the message.

Inside the card, the couple wrote: 'The Duke and Duchess of Cambridge thank you for your kind words following the death of The Duke of Edinburgh. Their Royal Highnesses have been incredibly moved by the many thoughtful messages they have received in recent weeks. They will all miss their much loved grandfather and great-grandfather, but your message has provided great comfort at this difficult time.'

The sweet message was accompanied by a smiling portrait of the Duke in military dress which was taken at the Queen's Diamond Jubilee Parade in 2012 at Windsor Castle, and featured a black border to symbolise mourning.

Royal fans around the world were shocked and saddened to learn of Prince Phillip's passing who had been a much-loved member of the royal family and fan favourite for his cheeky sense of humour.

Shortly after, Kate and William posted a loving tribute to their late grandfather on Instagram, with William writing: 'I feel lucky to have not just had his example to guide me, but his enduring presence well into my own adult life – both through good times and the hardest days.

'I will always be grateful that my wife had so many years to get to know my grandfather and for the kindness he showed her. I will never take for granted the special memories my children will always have of their great-grandpa coming to collect them in his carriage and seeing for themselves his infectious sense of adventure as well as his mischievous sense of humour!'

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