The Welsh actress’s support came as the trust said it was already half way to raising the money needed to buy Llyndy Isaf, a 614-acre farm in the Nant Gwynant valley which includes the Llyn Dinas lake. The campaign, which has received more than £500,000 in donations in a month, is the trust’s biggest countryside appeal since its drive to save Snowdon more than a decade ago.
The organisation fears that if it does not buy Llyndy Isaf the estate could fall into commercial hands, threatening its future.
According to the trust, the farm has been untouched by intensive farming for decades and is home to a wealth of wildlife.
The hills around the farm are also steeped in mythology, with legend telling of the battle between a white dragon and a red dragon which took place at the hill of Dinas Emrys that overlooks the Llyn Dinas lake. The red dragon won, becoming the national emblem of Wales.
Zeta Jones said: “The National Trust plays a key role in protecting and managing the Welsh countryside, the beauty and landscape of Snowdonia is truly unique and we have a once-in-a-lifetime opportunity to protect Llyndy Isaf in this stunning part of Wales for future generations.”