People Magazine
Updated Nov 12, 2018 @ 10:23 am
Credit: Rindoff Petroff/Suu/Getty Images

Welcome to the family, Arthur Michael William! Pippa Middleton, 35, and husband James Matthews, 43, gave their new baby boy this three-part moniker, The Mail on Sunday reports, citing the child’s birth certificate. The name Michael may honor James’ brother Michael Matthews, who died at age 22 while climbing Mount Everest in 1999. Michael is also the name of Pippa’s father.

The first cousin to Prince George, Princess Charlotte, and Prince Louis is settling in with his proud parents since his arrival on October 15th. Just like those little royals, he was born at the private Lindo Wing of St. Mary’s Hospital in London. His birth came just as the world was learning that Prince Harry and Meghan Markle are expecting a baby of their own in the spring.

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But Pippa’s news wasn’t made public until October 16th, followed by a statement from her older sister, Kate Middleton, and brother-in-law, Prince William, saying they are “thrilled” for the couple.

Only three days before the baby was born, Pippa and James had been among the 800 guests inside St. George’s Chapel and Windsor Castle for the wedding of Princess Eugenie and Jack Brooksbank, and smiled broadly as they strode past well-wishers after the ceremony.

The new member of the Middleton-Matthews family also will have a playmate on his father’s side: Spencer Matthews, the brother of financier James, welcomed his first child, a son, with his wife, model Vogue Williams, in early September.

Pippa and James married in May of last year at St. Mark’s Church in Englefield—and their royal nephew and niece, 5-year-old George and 3-year-old Charlotte, were among the bridal party. A friend previously told PEOPLE that settling down, “having children and leading a quiet life,” was always their desire.