When Lizanne and Lee Harris found out their children had been preached to at a school assembly by Warren Furman, an evangelical Christian and former star of the TV show Gladiators, it was the last straw.

The couple had already withdrawn their sons and daughter from the weekly religious assembly at their Cotswolds primary school, a state school with no religious character, after discovering that their offspring were being regularly made to watch re-enactments of Bible scenes. But following the revelation that Furman (perhaps better known by his on-screen name, “Ace”) had been teaching them about the word of God, the couple mounted a high court battle to protect their children’s right to freedom of belief.

Last week their case was settled out of court, with the school’s Church of England multi-academy trust agreeing to provide the Harris children and other pupils at the school who withdraw from the weekly religious assemblies with meaningful alternative activities. Their parents hope the decision could have far-reaching implications for other state schools holding religious assemblies across the UK, and could also put pressure on the government to repeal a 75-year-old law that makes it compulsory for non-religious state schools to conduct a daily act of collective, broadly Christian worship, unless the school has chosen to opt out.

It was actually quite heartbreaking, as a parent, to see that. It upset me. Lizanne Harris, mother

“This will pave the way for other parents,” said Lee, speaking to the Observer last week. “They offered everything we had asked for, plus a little bit extra,” said Lizanne. “They didn’t want to see the inside of court. I think they were worried, if we were to win, what legal precedent that would set.”

In their submission to the high court the Harrises argued that Christian worship at their children’s school in Burford, Oxfordshire, constituted indoctrination and was in breach of their right to freedom of belief under the Human Rights Act and the European Convention on Human Rights.

Under the settlement reached with the Oxford Diocesan Schools Trust (ODST) that runs the school, all pupils who withdraw from religious assemblies at Burford primary school will now be provided with a teacher who will deliver alternative age-appropriate activities and materials “designed to further the spiritual, moral, social and cultural development of all pupils, regardless of religion or belief”. The trust has also agreed its school leavers’ ceremony will no longer be held in the local church, Bibles will not be handed out to pupils as gifts again, and visitors will be asked to respect different children’s beliefs.

Lizanne said her children punched the air and shouted “yes!” when they heard the news. In the past, while their teachers and peers were engaging in collective worship or religious events, her children had been “left to their own devices” – supervised, but without any meaningful alternative activities to do, she said. “It was actually quite heartbreaking, as a parent, to see that. It upset me.”

Facebook Twitter Pinterest Warren Furman as Gladiator Ace – he taught children about the word of God. Photograph: ITV/REX/Shutterstock

Burford primary school is the Harrises’ nearest school and the only non-religious school in their area. “As a parent you want to be able to validate what the school teaches your children,” said Lee Harris. “But we were continually have to unpick the ‘truths’ they were learning at school.”

Humanists UK, which funded the Harrises’ £40,000 legal challenge, called on the government to issue new guidance to schools following the decision. “The government should make clear what schools need to do to ensure they are not breaching children’s human rights,” said spokesman Richy Thompson. The current law enforcing daily Christian worship in non-religious schools is “unworkable” and outdated, he said. “We get more complaints about collective worship from parents than anything else.”

The charity is now offering to support any other parent who wants to take similar action. “If a parent asks a school to provide an alternative to collective worship and the school doesn’t do it, then we will be encouraging the parents to get in touch with us.”

The charity has created a guide that parents can use to request a meaningful alternative to religious assemblies for their children at school – and Thompson expects many parents to do so, following the settlement. “We do feel quite optimistic that if a Church of England Diocesan Trust has reached the conclusion that they should give parents everything they asked for, then other schools would reach that conclusion too.”

Although the Harrises are equally hopeful that their case will help other parents, they feel frustrated and angry about how hard they have had to fight to secure a secular education for their children. They have received abusive messages as a result of their campaign, such as “I hope you and your family burn in hell”. “I’m disappointed in the school. They could have cleared this up a long time ago,” Lizanne said.

The ODST said it chose to settle for financial reasons. “A small community school has been placed at the sharp end of a national campaign,” said CEO Anne Dellar. “At a time when school funds are stretched, ODST took the pragmatic decision to avoid wholly unnecessary court costs.”

She said the school had been giving the children “educational resources to read and work through” when they withdrew from assemblies and stressed that it had acted entirely within the law and in the best interest of the children.

“Burford primary school is happy, successful and inclusive school. We are saddened the court case has diverted valuable funds and staff time.” The trust must now pay a combined £100,000 legal bill.

She does not expect the decision to affect other schools and stressed that the settlement reached was “a short-term, child-specific arrangement” that will lapse when the youngest Harris child leaves the school.

However, Thompson warned that other children at the school would be equally entitled to demand meaningful alternatives to collective worship at any point in the future. “If another parent turns around and says: I want the same thing the Harris parents were provided with, the Trust will then face potentially the same threat – will they behave any differently?”

The Department for Education said it had no plans to issue new guidance for schools and said that the terms of the settlement related to Burford primary school only. “There are no implications for schools nationally,” said a spokesman.