FROM the moment that Prince William began dating Kate Middleton two decades ago, he made it clear that his relationship with his in-laws was non-negotiable.

Since then, the close-knit Middleton family has been integrated into the fold of the Royal family and invited to key events such as Royal Ascot, the late Queen’s Diamond and Platinum Jubilees and the King’s Coronation.

Now Kate’s mother Carole has become ‘the driving force’ as the family helps care for the Prince and Princess of Wales in the wake of Catherine’s cancer diagnosis –  stepping into the breach to help look after George, ten, Charlotte, eight, and Louis, six.

• Proud mother Carole Middleton with her daughter, Kate, at  Royal Ascot in 2017

• A still image from Kate’s moving video message, in which she disclosed that she was undergoing chemotherapy

• Carole, right, watching over her grandson, Prince George, at the King’s Cup Regatta in Cowes in 2019

• Carole is always in the background, quietly helping her daughter bring up her family. Here, they are pictured at Cowes in 2019

• Carole, right, smiles at Prince George as they attend the Christening of Princess Charlotte in 2015

Carole, 69, lives with husband Michael, in a £4.7 million manor house in the village of Bucklebury, which is 32 miles from Adelaide Cottage, the Wales’ home in Windsor Home Park.

‘Carole has been the driving force keeping the family together with minimum fuss and maximum modesty,’ the source told The Independent.

‘She’s ferried and fetched George, Louis and Charlotte, taken them to school sports matches and given them endless support. She’s a real Mary Poppins-like figure.

‘She’s come to the rescue, provided reassurance and been a rock to Catherine and William as they come to terms with the news.’

Ingrid Seward, editor in chief of Majesty Magazine, said: ‘Carole and Michael are just as much family to William as they are to Catherine.

‘He loves Carole being around to help as she has been with the children from the beginning and it is easy and reassuring having her invaluable help.

‘Both with the children and keeping Catherine’s spirits up. She is a strong woman!’

It is now 18 years since Kate made her first official public appearance, attending Second Lieutenant Wales’s passing-out parade at the Royal Military Academy, Sandhurst.

• Kate Middleton with Carole and Michael Middleton sitting in the front row at Prince William’s passing-out parade at Sandhurst in 2007

• Carole and Kate are pictured together at London’s Olympia exhibition centre

But William did not just send his girlfriend an invitation. He also invited her parents Michael and Carole, who sat with her in the front row of the public stand.

Since then, the couple have been invited to a host of historic occasions, but it is behind-the-scenes that they have come into their own.

It is no surprise that  spending just one night at Kensington Palace with new-born son George, they decamped to the Middletons’ family home, where they posted a family photograph taken by Michael Middleton.