According to multiple reports, Thomas Kingston, the husband of Lady Gabriella and ex-boyfriend of Pippa Middleton, died on Sunday
Thomas Kingston also previously dated Kate Middleton's sister, Pippa Middleton.
The Middleton family was on hand to witness the historic event on Saturday.
Pippa Middleton and James Matthews recently welcomed their third child.
The author's baby bump could be seen in June during her appearance at the Queen's Platinum Jubilee concert.
Queen Elizabeth made an appearance on the Buckingham Palace balcony on Sunday, marking the end of the Platinum Jubilee celebrations.
Kate Middleton's sister is already mom to Grace and Arthur.
Pippa Middleton, as well as Princess Eugenie and Princess Beatrice, also made an appearance.
Kate Middleton's younger sister has welcomed a baby girl.
Reports first surfaced of Pippa's pregnancy back in December.
Kate Middleton's sister is going to be a mother of two!
These ladies know how to beat the heat in the hottest way possible!
Pippa made a trip to St. Barts last year at the same time.
The bride-to-be's mother, Sarah Ferguson, did attend the event.