The number of children who were toilet-trained before starting school this year has increased significantly in a city where parents were given potty training guides with their first school offers.
York was the subject of the city-wide pilot, which also put on workshops for parents and offered special training for early years staff.
Twenty local authorities across England are now signed up to launch similar schemes to tackle the number of pupils starting school without being fully toilet-trained.
The government said the pilot's results were "encouraging", and confirmed they were committed to 75% of pupils reaching a good level of development at the end of their first year in school by 2028.
Since April this year, parents across York have been targeted via GP surgeries, pharmacies, family hubs, schools and nurseries with information and offers of support on how to potty-train their child ahead of starting school.
Potty training guides were sent out to all families across York who had a child starting reception in September - with the aim that all children could use the toilet independently by the time they started school, except those with medical issues or special educational needs.
The results from all 55 mainstream primary schools across the city, shared exclusively with BBC News, suggested there had been a 43% drop since last year in the number of children who were not fully toilet-trained when they started school.
Across York last September, 148 out of 1,364 reception pupils (11%) were recorded as not being toilet-trained when they started school. This year, that fell to 85 reception pupils out of 1,374 (6%).
Parents Natalie and Lucy, who both have daughters starting reception next year, have welcomed the extra support on offer.
Lucy said she had noticed the drop-in sessions on potty training in her local children's centre and thought it was a "really good idea".
"I think it's really important that children are more prepared for that aspect of starting school," she said.
Natalie said getting her daughter Freya potty-trained in time for school has been a priority, but feels there is a lot of pressure on parents to do so.
"I think going to school is hard enough for children," she said.
"But for me it was really important that she's confident enough to use toilets, to be independent, to be able to go without relying on the help of teachers perhaps in an environment where they've already got lots of children to look after."
Natalie said the popularity of disposable nappies might be a reason why parents often wait longer to potty train.
"When I was little, we still had the terry towelling nappies and they had to be washed and hung on the line. So I think with disposable nappies it's easier," she said.
York councillor Bob Webb said the impact of the scheme had been "so positive" for both schools and families.
But he acknowledged a potential "gap in support" for parents between seeing health visitors with their toddler, and the child later arriving at school.
He said the key to the scheme's success was collaboration across health visitors, schools and other community settings, but that there was "always more that could be done at an earlier age".
Twenty local authorities across England have now committed to adopt York's model, developed by Kindred Squared, and use it to encourage earlier potty-training in their areas.
They include:
North Lincolnshire
Suffolk
Solihull
Rotherham
Hampshire
Halton
London Borough of Redbridge
London Borough of Hounslow
Cheshire West and Chester
Just over two-thirds of children in England (68.3%) leave reception class with a good level of development - a key measure of school readiness which includes things like communication skills, as well as physical, social and emotional development - according to the latest government stats, external.
That means they were assessed by teachers on being able to complete tasks like going to the toilet and paying attention in class.
The government has said it is still committed to increasing that proportion to 75% by 2028.
Early Education Minister Paul Waugh said it was "encouraging to see this pilot helping more children develop the confidence and independence they need before starting school", stressing the importance of parents taking early steps towards toilet training.
In York, Mould said she hopes next year's parents will take on potty-training even earlier.
"Ideally we'd be at the point where [children] don't need that support when they get here, because they've already been trained by the time they get to us."
