The Duke of Cambridge waas also ful of praise for the portrait.
Prince William said:: "It's beautiful, it's absolutely beautiful."
The Cambridges later attended a private breakfast reception at the London gallery to mark the unveiling.
More top news
A chilly night to come with a mixture of low cloud, mist and fog. More sunshine will return tomorrow.
Campaigners want a sainthood for a priest from Essex who died on the Titanic after he stayed behind to pray with the stranded passengers.
Police have released CCTV pictures showing Clive Howard's car cruising the streets of Norwich