The Queen has always had a close relationship with her grandson Prince William, and gets on just as well with his wife, the Duchess of Cambridge. Over the years, the pair have undertaken many royal engagements together - their first being on 8 March 2012 - nearly a year after William and Kate's royal wedding. The pair [pictured] enjoyed some one-to-one time, as they travelled to Leicester to mark the first date of the Queen's Diamond Jubilee tour of the UK.
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Kate has always been very respectful of the Queen, and gave only daughter Charlotte the middle name of Elizabeth. The Duchess has previosuly spoken about her grandmother-in-law during a rare interview in ITV documentary, Our Queen at 90. Kate revealed in it that she didn't know what to give the Queen for Christmas but settled on homemade chutney made from her own grandmother's recipe. "She (the Queen) really cares," Kate said. "I can remember being at Sandringham, for the first time, at Christmas. And I was worried what to give the Queen as her Christmas present. I was thinking, 'Gosh, what should I give her?' I thought back to what I would give my own grandparents. And I thought, 'I'll make her something.' Which could have gone horribly wrong. But I decided to make my granny's recipe of chutney."
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Kate added: "I was slightly worried about it, but I noticed the next day that it was on the table. I think such a simple gesture went such a long way for me and I've noticed since she's done that on lots of occasions and I think it just shows her thoughtfulness, really, and her care in looking after everybody."
Take a look through our gallery at all the best photos of the Queen and Kate...
As they attended the Christmas Day church service in Sandringham in 2013, the Queen and Kate warmly embraced each other.
The Queen and Prince Philip posed with Prince William and Kate at the annual Diplomatic Corps Reception at Buckingham Palace in December 2016. The special occasion gave royal fans a chance to see the Cambridges in a formal photo with William's grandparents.
What's so funny? The Queen and Kate were in stitches as they watched a children's sports event at Vernon Park in Nottingham back in 2012.
Three generations of the royal family – Queen Elizabeth, the Duchess of Cambridge and little Princess Charlotte in the monarch's vintage pram – at the little Princess' 2015 christening at the Church of St Mary Magdalene in Sandringham, Norfolk.
In 2012, Kate was the lady in red as she joined the Queen and the Duchess of Cornwall aboard the Spirit of Chartwell during the Diamond Jubilee Pageant on the River Thames in London.
As the Queen passes by, Her Majesty receives an elegant curtsey and beaming grin from granddaughter-in-law Kate. The royal family were attending the Easter Day Service In Windsor at St George's Chapel on 16 April, 2017.
Photo: Wire Images
The Queen and the Duchess of Cambridge both went for tailored looks as they arrived at Kings Cross St Pancras Station in London on the first date of the monarch's Diamond Jubilee tour of the UK.
The Duchess of Cambridge and Queen Elizabeth were right at home in 2011 as they viewed the exhibitions for the summer opening of Buckingham Palace.
The two royals stopped to view Kate's Sarah Burton for Alexander McQueen couture wedding dress at the 2011 Buckingham Palace exhibition.
The Queen and the Duchess wore perfectly complementing looks in the hues of the British flag as they arrived at a 2014 reception for the dramatic arts at Buckingham Palace.
The Duchess of Cambridge seemed to be pointing out the sights to Prince William's grandmother on the balcony at the Council House, in Nottingham back in 2012.
Prince William was in the middle of two of his favorite ladies as the Queen and Kate Middleton had a chat on the balcony of Buckingham Palace in 2012.
The Queen and the Duchess of Cambridge shared a moment at Leicester's Clock Tower during a visit to the city as part of the Diamond Jubilee Tour.
Three's company! In 2013, the Duchess of Cambridge joined Queen Elizabeth and the Duchess of Cornwall to check out some gift baskets during a visit to luxury department store Fortnum and Mason in London.
The royal trio shared plenty of laughs during their 2013 visit to Fortnum and Mason.