The Duchess of Cambridge brought fun to a playground on a visit to a primary school – and one excited little boy said he had “never seen a princess before”.

Kate was at the Blessed Sacrament School in Treaty Street, Islington, yesterday afternoon to see the work of a project she launched to help families affected by addiction – a cause royal aides said is very important to her.

Her arrival attracted lots of onlookers keen to catch a glimpse of royalty while children sat cross-legged waving England flags and cheering.

Kate, wearing a coral dress by Goat, knelt down and chatted to the excited children, asking them about their favourite subjects and what they like most about school.

Five-year-old T’shai said he enjoyed it, adding: “Because I’ve never seen a princess before.”

Nathan, also five, said he told Kate his favourite thing was “books”, while Ezekiel, four, said “lunchtime and playing”.

Kate was joined by comedian John Bishop, with whom she launched the charity effort last year, and she spoke with people involved in a pilot programme for the school-based project M-PACT (Moving Parents and Children Together) Plus.

The initiative, funded by The Royal Foundation and Comic Relief, and delivered by charities Place2Be and Action on Addiction, of which the Duchess is a patron, aims to provide early support for schoolchildren affected by a parent’s drug or alcohol misuse.

Bishop had the Duchess giggling at the end of the visit when he appealed to the press not to focus on what the “style icon” was wearing, where the clothes were from or what hairstyle was in place – but to focus on the project.

“Basically, don’t make the story about me,” he joked.

Speaking about his passion for the issue, Bishop said a lot of it is down to how “fleeting” childhood is, adding: “We haven’t got the time to waste.”

Bishop said Kate is “genuinely committed” to the issue, and hailed the involvement of the Royal Foundation.

“What’s good about it is that it will hopefully de-stigmatise the whole area,” he said.

“Addiction doesn’t care what social class you’re from. It’s across the board. The levels of addiction in Knightsbridge will be as high, if not higher, than some of the most deprived areas in the country,” he said.

“I think, from the brief conversations I’ve had with her, she’s committed to it as a person and probably even more so now as a mother, because you realise children are such fragile things and you’ve got to try and support them when they’re at their weakest.”