Sienna Miller has a bun in the oven! Related: How Kylie Jenner & Timothée Chalamet Celebrated Thanksgiving Amid Breakup Rumors! The Anatomy of a Scandal actress debuted her exciting news at the British Fashion Awards on Monday, sharing a peek at her bump in a sheer Givenchy dress. See (below): View this post on Instagram A post shared by Vogue (@voguemagazine) She's radiant! The 43-year-old actress has been with partner Oli Green, 28, since late 2021. The pair went on to welcome a daughter together two years later.