The special family tradition behind Princess Kate's 18th birthday gift

The Princess of Wales , along with her siblings Pippa Matthews and James Middleton , celebrated their 18th birthdays with a cherished family tradition, lovingly upheld by their parents, Carole and Michael Middleton .

In his new memoir, Meet Ella: The Dog Who Saved My Life , Kate's younger brother James has given many sweet details into their upbringing – including how their milestone birthday was marked in a meaningful way.

© Max Mumby/Indigo

"Throughout my teens, my two obsessions, with dogs and all things mechanical, flourish," James recalled. "Weeks before I am due to turn 18, in the spring of 2005, my father asks what I'd like for my birthday.

"He gives me a choice: a little second-hand Peugeot 206 or a dilapidated and ancient tractor. A tractor? Yes, he knows in his heart that I'll choose the quirky option - and I do."

The dad-of-one added: "Dad and I load it onto the trailer. As we drive back to Berkshire, passing through lanes glowing with wildflowers, I can't help but reflect on how thrilled I am with my gift."

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Speaking fondly of his sisters' milestone birthdays, he remembered: "Catherine and Pippa were given beautiful jewellery for their 18th birthdays, but mine is a tractor."

He continued: "I've decided to honour her by naming her Tilly, after our beloved family dog."

As a brother to the future Queen, James is aware of the enormous public interest in his family.

In his new book, the 37-year-old shares a heartfelt story of survival as he opens up about his battle with clinical depression and feeling suicidal. He also wrote about both his siblings and parents with love and openness, while protecting their privacy.

In one part, James revealed how he took parenting advice from his sisters Kate and Pippa .

The Princess shares Prince George, Princess Charlotte, and Prince Louis with her husband Prince William, while Pippa is also the mother-of-three to Arthur, Grace, and Rose with her husband James Matthews.

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"It's been wonderful, seeing them become mothers and being so dedicated and strong. I'm in awe of that," James said, before quipping: "I've been fortunate to see how my sisters have done it and take tips along the way – some I take on board, and others I'm like: 'Hmm.'"

Of borrowing the children's hand-me-downs for his own son Inigo, he added: "They are milestones, because [my sisters] remember when their child was wearing something, and how old they were – it takes them back. It's been a lovely thing for them."

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