Showing the two together, with Tara wearing a pair of bunny ears, the image is captioned: "In loving memory on this Easter Sunday of my own little mischievous (sic) Easter bunny who is dearly missed".
The two were great friends for many years, with the late socialite often pictured in locations around the world alongside the Blue boyband member - and later "Hollyoaks" actor, reported Digital Spy.
When Tara died back in February, Duncan was one of the first to pay tribute to her in another post on Instagram.