This is from the Passport Office website :
"FROM
26 OCTOBER 2004 ALL CHILDREN WILL NEED THEIR OWN PASSPORTS TO ENTER THE USA.
The US has granted an extension of its Visa Waiver Programme to holders of non-machine-readable British passports travelling to the United States.
This means that all British passport holders, including children, travelling to the USA under the Visa Waiver Programme will need their own machine-readable passport
with effect from 26 October 2004, rather than from the original date of 1 October 2003.
From 26 October 2004 anyone without a machine-readable passport, including children who are currently on a parents passport will need a visa to travel to the USA. Airlines will not allow children without their own passports or a US visa for them in an adults passport to board flights to the USA. So if you are planning a visit to Walt Disney World, or anywhere else in the USA, we would advise you to apply in good time for passports for all children who will be travelling, or to contact the US Embassy about obtaining visas.
If you want more info, this is the link to the website :
UK Passport Office
Hope this clears it up for you !
