Up until now the information has been kept strictly under wraps, with aides instructed not to give the game away.
But what the world's press failed to discover, children at an Oxfordshire school found out without too much trouble.
Pupils at Rose Hill Primary School learned what the Duchess of Cambridge and her husband have called their new pet, a black cocker spaniel.
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When one child gave Kate, 30, a toy dog to cuddle she said: "Why don't we call it after my dog? He's called Lupo".
The royal had come to publicise the work carried out of the charity, The Art Room, in her capacity as patron.
Buoyed by the success of her previous solo engagements, Kate looked confident as she chatted and shook hands with well-wishers.
And in keeping with the art theme, she showed her talent for diplomatic dressing by donning a coat-dress by Irish designer Orla Kiely, aptly known as the queen of prints.
Her dress, which was reduced from £325 to £162.50 in the sales, ended up with a blob of red paint on the cuff in an arts class.
The school's little charges were asked to read Edward Lear's poem The Owl and the Pussycat to their VIP guest, and then paint pictures inspired by the story.
And the mishap happened when Kate, a History of Art graduate, got stuck in wearing an apron embroidered with the name 'Miss Catherine'.
Her attitude won praise from Lisa Hancock, the charity's manager at the school.
"She seemed to have as much fun as the children and seemed very relaxed. She had all the right language and was very calm and gentle."
The Art Room charity uses creative therapy to raise self esteem and independence amongst disadvantaged children and teenagers.
Its founder and director, Julie Beattie, described it as "one of the smallest charities in the country" and is thrilled that the Kate is helping raise its profile.
After her first stop, the Duchess headed to Oxford Spires Academy School where the organisation also has facilites and runs workshops.
Watch: Prince William takes George to meet his sister
It's a little princess!