Why are so many four-year-olds not potty-trained before school?

For some parents the countdown to starting school means buying uniforms, labelling water bottles and trying to squeeze in one last summer holiday.

For others there is a more basic question to tackle: can their child use the toilet on their own?

According to a survey by the charity Kindred Squared, almost a third of children starting school in the West Midlands last year were not fully toilet-trained and 42% of those arriving in reception were deemed not school-ready by primary school staff.

This week the charity announced its potty-training scheme, which provides resources and support including increased training for nurseries, schools and professionals, will be rolled out in Solihull.

In a pilot in York, which began in April, parents were sent potty-training and school readiness guides with their offers of a school place. Workshops were held, resources distributed and support offered through GPs, pharmacies, libraries and community hubs.

As a result, the number of non-toilet-trained children starting reception fell by almost half.

Rachel, a mother-of-two from Nottinghamshire, is one of Lu-Quee's clients. She tried to toilet-train her son when he was three but he had problems with withholding stools.

She works as a teacher but said being on the other side of the problem as a parent was very different.

"I'd say as a teacher, I feel I'm quite an informed parent in this area," she said. "So I was thinking, 'I know what's going on but I don't know what to do'.

"It's not the parent, it's not being lazy; it's hard and it's a lot of effort," she added.

She was told she would not be able to access funded support for her child until he was five, and it was not until the end of his reception year that the family received help.

Now aged eight, her son is awaiting an assessment for ADHD, which Rachel believes could have affected aspects of his development despite going unnoticed in his early years.

"Withholding can be trauma-informed and it can be because of passing something that has hurt at some point or someone has reacted badly to them having an accident," she said, adding she believed embarrassment and shame had contributed to her son's difficulties after he had an accident at nursery.

Helen Davies, a health visitor and children's nurse based in Stafford, said children who repeatedly had accidents may be frightened of the toilet, leading to constipation.

"A child who is struggling may be frightened of the toilet, withholding poo or experiencing constipation. Repeated accidents should prompt curiosity about what is getting in the way rather than an assumption that parents have not tried hard enough," she said.

Bailey, a former reception teacher and early years lead, said she had worked in "deprived and affluent areas" and had seen inequalities in school readiness.

"It comes down to income," she said. While some parents were able to buy parenting books, she said those on lower incomes had less access to information.

"Books are quite expensive," she added, suggesting families could be given free toilet-training resources when their children turned two.

Davies, who provides one-to-one guidance through her company Essential Parenting, said families may not be getting "timely, consistent support before difficulties become entrenched".

She said financial pressure, parental stress, limited opportunities for play and difficulty accessing early years provision and professional advice could make preparing for school harder.

"Public services are essential, particularly for families who cannot afford private support," she said.