William Slim Drive has been officially renamed to Gundaroo Drive ahead of its long-awaited duplication.

Street signs are yet to be updated after the name was quietly changed last Friday.

The name change will simply extend the existing Gundaroo Drive from Gungahlin to Belconnen.

ACT Planning Minister Mick Gentleman signed off on the change following allegations Sir William Slim sexually abused children in the 1950s.