Lilibet's first birthday celebration at Windsor Castle: Prince Harry and Meghan invited royal kids

Prince Harry and Meghan Markle reportedly had a "relaxed and casual" birthday party" at Windsor Castle for their daughter Lilibet as she turned one on June 4, according to reports.

The Duke and Duchess of Sussex have reportedly hosted an informal garden party at Frogmore Cottage in Windsor for their daughter’s milestone birthday and they welcomed some the tot’s royal cousins to share in the celebrations.

The Queen's great-granddaughter's birthday party took place on the royal estate and included picnic food, party games, balloons and a cake, according to The Sun.

Mike and Zara Tindall’s three children eight year old Mia, three year old Lena and one year old Lucas, as well as Peter Phillips and Autumn Kelly’s two daughters 11 year old Savannah and Isla, ten, were said to be invited to the event.

Meanwhile, Lilibet's cousins Prince George and Princess Charlotte were out and about with their parents Kate Middleton and Prince William on Saturday, as they visited Cardiff Castle and had front row seats for the Party at the Palace for the Queen's Jubilee.

Meghan and Harry's arrival arrival in the UK for the Platinum Jubilee celebrations has sparked speculations that the Sussexes could get Lilibet christened at St George's Chapel in Windsor.