File photo: Kate, who is expecting her third child, is again suffering from hyperemesis gravidarum which plagued her during the early stages of her first two pregnancies. Picture: AP

London - The Duchess of Cambridge has tried ginger biscuits to combat her severe morning sickness, Prince William has revealed.

Kate, who is expecting her third child, is again suffering from hyperemesis gravidarum which plagued her during the early stages of her first two pregnancies.

When Iris Orrell. 98, told William she had a similar illness when pregnant, the prince said his wife, 35, had tried the spice.

The Duke met her at an event celebrating the Metropolitan and City Police Orphans Fund, of which he is patron.

At the Guildhall in the City of London, William asked the mother of three: "Did it get worse with each pregnancy?” and was told it did. 

Orrell said her doctor had advised her to try "dry biscuits" and the Duke replied that ginger was said to help with stomach upsets. 

He added: "Ginger biscuits – but there’s not much ginger can do to stop that – we’ve done all that."