PIPPA Middleton attended the launch of the Mary Hare Primary School Appeal last week.
The appeal hopes to raise £6m to build a new primary school on the Snelsmore Campus, the site of the secondary school.
Some of this will be raised through the sale of the current Grade II-listed building at Greenham.
Ambassador for the school Ms Middleton said: “There are many good reasons to support the primary school project and I am delighted that the appeal launch has been so successful.”
Principal and chief executive of Mary Hare School Peter Gale said: “The advantages of moving to a new school on our campus are considerable.
“We have been very happy in Greenham and will keep fond memories of our time there, but it is time for us to have a 21st-century school.”
The Grade II-listed building, which houses the current primary school, no longer meets the needs of the pupils and is difficult to maintain.
The new primary school will include a state-of-the-art speech and language and audiology suite.
There will be additional space for one-to-one or small group sessions and all rooms will be acoustically treated with up-to-date modern facilities.
It is hoped the new school will be completed by 2020.