The veteran British actress made a splash when she was photographed in the two-piece while on vacation in 2008 and the pictures were published around the world.
Now The Queen star has handed over her beloved swimsuit to raise cash for Age UK's Spread the Warmth campaign, which provides thousands of older people with food packages, blankets and heaters.
She tells U.K. morning show Daybreak, "I'm saying farewell to it a little bit regretfully but hopefully it will go to someone who will fill it with as much aplomb as maybe I did... It happens to be one of the best bikinis in the world because it fits! The minute I bought it I loved it because it's so hard to find a bikini that fits if you've got bosoms like I have.
"I would love it to raise money for an organisation that I support called Age UK. I love the idea of this little flimsy summer thing going towards helping old people stay warm and comfortable and toasty in the wintertime. Age UK is a wonderful organisation so I'm hoping that they can raise money with it."
Fans can enter a prize draw to win the bikini by making a donation to Age UK via ITV.com/Daybreak.