Other notable guests there to toast Prince Louis were Prince Charles and Camilla, Kate's parents Carole and Michael Middleton, her sister Pippa and her husband James Matthews, and hot bearded Middleton brother James. The event took place inside of St. James's Palace.
Her Majesty, 92, is due to travel back from Norfolk Monday and has a busy week ahead with celebrations marking the centenary of the RAF on Tuesday, as well as Trump's visit to Windsor on Friday.
The young prince, who has an older brother George, (4) and sister Charlotte (3) was baptised using water from the River Jordan.
Queen Elizabeth II kicked off a day of engagements in a pair of patent leather heels, but switched into her comfortable favourites later on in the day. It is a replica of the gown worn by Queen Victoria's daughter for her christening in 1841. The Duke of Sussex purchased a first edition of Winnie-The-Pooh, worth close to $11,000. According to the site, she also wore matching Manolo Blahnik suede pumps and a hat from Stephen Jones Millinery.
She wore one to Princess Charlotte's christening in July 2015 and repeated the look for the Trooping of the Color in July 2016 and a commemoration ceremony in Belgium in 2017.