Cate Blanchett was inspired to name her son Ignatius by children's book 'Captain Underpants'.

The 'Cinderella' actress has joked she was ''hallucinating'' when she chose the name straight out of the Dav Pilkey-penned children novel series.

She said: ''We've got Dashiell, Roman, and Ignatius. You run out of ideas by the time you get to number three. So Dashiell came from Dashiell Hammett and Roman, from Roman Polanski but it's also the French word for 'book'.

''And then Ignatius came from 'Captain Underpants'. There's a particular edition called 'Professor Pippy Pee Pee Poopypants and the attack of the talking toilets' and I was eight months pregnant and hallucinating.''

The name featured in a list of names that the lead villain creates in order to make his moniker seem less embarrassing.

Speaking on Jimmy Kimmel Live!, the 46-year-old actress - who has her three sons and adopted daughter Edith with husband Andrew Upton - added: ''There's a section in the book where he gets so upset because everyone teases him about his name that he forces the world to change their names.

''They have this interior code and they give an example of names and you get down to 'I' and the example of the name is Ignatius and it was like the Virgin Mary going, 'I must call him Jesus.' I said Ignatius must be his name. My boys go to a catholic school and every second child is called Ignatius.''