Kate, 39, met Children of the 2020s project leaders at University College London, yesterday, including Professor Pasco Fearon. The duchess said: "Our early childhoods shape our adult lives and knowing more about what impacts this critical time is fundamental to understanding what we as a society can do to improve our future health and happiness."

       Researchers want to know how certain factors affect children's social, cognitive, and language development, as well as their mental health and readiness for school.

       Up to 8,000 families whose babies were born in April, May and June this year will be recruited for the project.

       Kate, who launched the Royal Foundation Centre for Early Childhood in June, is to carry out other study-related engagements in the future.