"This morning at 3:55am, we welcomed our son into a quiet London hospital... He is beautiful and healthy. We feel truly blessed," Spencer Williams wrote on Instagram

A built-in best friend for Pippa Middleton‘s baby has just arrived!

Spencer Matthews — the younger brother of Pippa’s husband, James Matthews — welcomed his first child, a son, with his wife, model Vogue Williams on Wednesday.

“This morning at 3:55am, we welcomed our son into a quiet London hospital… He is beautiful and healthy,” Spencer wrote on Instagram alongside a black and white photo of his hand clutching his son’s tiny fist. “We feel truly blessed.”

Added Spencer, “Couldn’t be more proud of @voguewilliams ❤️.”

Credit: Vogue Williams Instagram; Nils Jorgensen/REX/Shutterstock

Williams shared the same message, but posted an image of the little boy’s legs in striped blue and white pants. Neither revealed the new arrival’s name.

The baby comes shortly before Pippa and James are set to welcome their first child.

The Made in Chelsea star, 30, recently revealed on U.K. talk show This Morning that they feel “very blessed” that the children will be so close in age.

“I think it will be great for the kids to kind of grow up together. We’re all looking forward,” Spencer said.

In addition, Pippa’s child will also be very close in age to another cousin: Kate Middleton and Prince William‘s third child, Prince Louis, who was born in April.

Pippa Middleton and James Matthews (left); Vogue Williams and Spencer Matthews
| Credit: Dave Benett/Getty; Venturelli/WireImage

Although Pippa is following in the footsteps of her big sister and keeping the sex of her baby a surprise, Williams accidentally let it slip during a talk show appearance in April that she would welcome a boy.

“I know it’s bad to say, but I was kind of hoping the first child would be a boy so purely if you have girls afterwards, which we’d very much like to have, I always thought it’s nice to have an older brother,” Spencer said on This Morning.

And he added that they likely won’t stop with one child: “We’d like to have at least three in an ideal world.”

Spencer and Williams got engaged in February, just a month before sharing their exciting baby news.

Sharing a picture from Hello! magazine on Instagram in March, Spencer wrote, “So… I’m going to be a father! Couldn’t be happier to be sharing these times with the love of my life @voguewilliams . We feel truly blessed ❤️”

The couple tied the knot in June on the Spencer family’s 30,000-acre estate in Scotland.