The pair is said to have fallen in love with Britain and want their very own intimate royal wedding after their friend suggested the place, reported Daily Star.
"They both adored Kate and William's wedding and wanted to do something similar for themselves. They don't want a big flashy wedding but they liked the idea of marrying somewhere historic like a castle.
"But then Princess Beatrice suggested the Orangery at Kensington Palace and Mila and Ashton think it's the perfect setting. They want a small ceremony in front of just a few family and friends," a source said.