updated 01/08/2012 AT 1:25 PM ET
•originally published 01/08/2012 AT 2:30 PM ET
Although royal aides say she’s planning a “low-key” celebration of her 30th birthday on Monday, the Duchess of Cambridge was all glammed up for her final night as a 20-something.
Kate, in lacy floor-length gown by Alice Temperley and her own jewels, joined husband Prince William at her first royal film premiere – for War Horse – in London’s West End.
Just before their arrival, a drizzle started to fall, forcing William to hold an umbrella above them for their red carpet stroll.