The poorest children are missing more school and falling further behind classmates, research shared with the BBC suggests.

According to new analysis by the Education Policy Institute (EPI) – which looked at pupil performance after the Covid-19 pandemic – children from the lowest income families are now up to 19 months behind peers by the time they are 16 years old.

Education Secretary Bridget Phillipson told BBC Panorama Covid had led to a “serious and profound shift” in attitudes to attendance. She said lockdowns had cast “a long shadow” over the life chances of the youngest children.

The latest statistics for persistent absence show 15% of primary children in England have missed at least one in ten days of school this school year – up from about 8% before Covid.

It comes as the gap between the poorest students and other pupils had mainly narrowed before the pandemic, following years of effort by schools.

However, the report suggests it is getting worse. The gap – which is measured using GCSE results – would reduce from 19 months to 15 months of learning if school attendance was the same for all pupils, it says.

Natalie Perera, from the EPI, said it is the first time “a very clear link” has been made between how much children from the lowest income families attend school, and how far behind other pupils they have fallen.

Her team looked specifically at children who have received free school meals in the past six years, which means the family income is less than £7,400 a year after tax and not including benefits.

Ms Perera said more research was needed to understand why these children struggled to be in school, with possible factors including poor housing and mental health.

It is five years since the UK went into lockdown, when schools closed to most children.

Playgroups and nurseries also shut, with parents of babies and toddlers isolated from their extended family. There were other changes too, as health visitors were re-deployed or in contact with parents only online.

Panorama has heard from families and teachers about the impact on these children, who are just starting or are still in primary school.

Schools say some have delayed speech and understanding of words, or have slower social or emotional development, or they lack basic skills normally picked up through play.

Professor Catherine Davies, from the University of Leeds, says some children missed out on “fundamental skills” they need to make sense of school and get on with wider groups.

At Queen’s Drive Primary School, in Preston, teaching assistant Sarah Barraclough has been trained in a national programme to help four and five-year-olds in England with speech and language.

She says the impact of Covid has been “huge” and if they don’t learn to say and understand more words, children then become isolated. “You’re lonely and not getting involved in the games in the playground,” she says.

Emaan, now aged four, was born during the first UK lockdown and is one of the children receiving help through Nuffield Early Language Intervention (NELI).

His parents, Ruby and Charles, really notice the difference between Emaan and his older brother. During the pandemic, Emaan barely went out and met other people.

Charles says there is a “stark difference” between their sons and that Emaan is a lot more clingy.

The NELI programme to train teaching assistants is funded until the end of this school year in England. But beyond then, funding has not yet been confirmed.

The government has set a 2028 target for 75% of children – up from 68% – to reach a good level of development by the time they leave reception.

Some of the cultural shifts caused by the lockdowns and partial school closures could prove to be the hardest to resolve.

The education secretary told the BBC the pandemic had profoundly changed attitudes towards attendance. She said it was important the youngest pupils got the “support they need to thrive”.