Kate Middleton reveals she can't believe how fast Prince George is growing up as she meets mums - best photos

The Duchess of Cambridge met young mothers and their children as she made an unannounced visit to the Family Nurse Partnership in Southwark, south London on Thursday morning.

The FNP is a voluntary home visiting programme for first-time parents aged 24 and under. The parents are partnered with a specially trained family nurse who visits them regularly, from early pregnancy until their child is two. 

The programme supports young mums to have a healthy pregnancy, improve their child's health and development, and reach their goals and aspirations.

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Mum-of-three Kate, 37, heard about how the programme has helped them and their children. Her visit to the Sunshine House Children and Young People’s Health and Development Centre is part of her work with the Early Years initiative.

Two weeks ago the Duchess dropped daughter Princess Charlotte, four, off for her first day at Thomas's Battersea school. 

“She said children grow up so quickly and she can’t believe that George is six already” young mum Chloe Koroma, 23, said after chatting to the future Queen.

MORE: Kate Middleton turns heads in trousers and polka dots at the Family Nurse Partnership

The Duchess formed a steering group, made up of health-care experts and academics last year, to highlight the importance of early intervention to give children from all backgrounds the best start in life.

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Kate discussed the scientific theory of attachment with experts from the Family Nurse Partnership.

The Duchess looked elegant in a polka dot blouse and cropped wide-leg trousers with her Gianvito Rossi pumps for her engagement. 

She beamed as she was given a posy as she departed from the Family Nurse Partnership. 

We last saw Kate when she viewed the new Back to Nature garden at RHS Wisley, where she arrived with celebrity chef Mary Berry on a tractor. The Duchess had some sweet interactions with children at the festival, including a funny moment with three-year-old Dylan Corbin, who had a tiger painted on his face.

On Thursday 26 September, the Duke and Duchess of Cambridge will travel to Birkenhead to officially name the UK’s new polar research ship, the RRS Sir David Attenborough.