The boss of the UK’s leading children’s charity has attacked the Conservatives for their failure to improve outcomes for children, saying that, while they were in power, “pretty much every indicator” went in the wrong direction.

In a frank interview days before he steps down, NSPCC chief executive Peter Wanless said ministers had “good intentions”, citing a review of children’s social care and online safety reforms – but that in the end, “you’ve got to be judged by the actions”.

“Child poverty has got a whole lot worse. Spending on children has gone up, but increasing amounts of it has gone into the price of failure rather than early intervention and prevention,” he said. Resources to support early intervention are down 44% since 2010 as the number of children taken into care has risen by 28%.

Speaking to the Observer after 11 years at the charity’s helm, Wanless also attacked social media giants for prioritising profits over people, condemned the “morally repugnant” failure of successive governments to ban smacking in England – as it is in 67 countries – and weighed in on calls to block children from using social media, as Australia plans to do.

In response to some campaigners arguing for a social media ban, he said that while he wasn’t “indifferent” to dangers online, banning social media could do more harm than good – and argued that blanket restrictions on digital access were a “blunt instrument” that risked creating a “huge cliff edge” later in life.

“It’s an easy option for adults to shut them off and say: ‘This isn’t for you’,” Wanless said. “But childhood, to me, is not risk free. It’s about enjoying life with guardrails. So I think we’ve got to get the guardrails right for the online world, which doesn’t mean kicking kids off it.”

There was no guarantee that restricting access would make children safer anyway, Wanless said, “because they’re resourceful and they’ll find ways of accessing all this stuff in another way”.

Meanwhile, the potential consequences were severe. “There are so many connections, friendships and learning opportunities now accessible online,” he said. “To deny the opportunity to benefit from all that would probably set back education and child ­development considerably for the price of potentially making children safer but potentially not.”

Wanless was also highly critical of social media giant Meta, which he accused of being “in denial” after the self-harm death of a 14-year-old girl who had viewed graphic content on Instagram, claiming that it and other tech firms prioritised profits over people. After Molly Russell’s death in 2017, the company was “terrible”, he said. “They were in denial all the way through, wriggling and refusing to share information and refusing to share their research.

“I remember having a meeting with Instagram when they came over in the wake of Molly Russell dying. And nothing was too much trouble, and everything was going to improve.”

Over his time in charge of the NSPCC, he said he had countless meetings with the company and other social media giants in which they promised changes. “I’ve lost count over the last 10 years of the number of times I’ve sat in conversations with the companies, and they’ve patted me on the head and said: ‘Thank you very much. You’re doing such important work, and we’re really keen to achieve the same as you.’”

Eventually, Meta introduced some improved design features and now “things aren’t as terrible as they were. But children are still coming across all sorts of material that they shouldn’t.”

Meta says it has launched 50-plus tools to improve child safety, including teen accounts and “research-backed” messages when someone searches terms linked to self-harm or suicide. But a damning study reported by the Observer this weekend casts doubt on Meta’s claim to have significantly improved its moderation, finding that Instagram is still failing to remove graphic self-harm content, with processes described by researchers as “extremely inadequate”.

Wanless also singled out Snapchat, which offers a disappearing messages feature and came out top of a list of the worst platforms for child grooming in recent research by the NSPCC. Snapchat says it offers a range of safety tools and that even though content on the app disappears, it preserves illegal and harmful material in case police get in touch with a legal request.

But in the year to March 2024, of the 1,824 grooming offences reported to police where the platform was identified, Snapchat accounted for almost half (48%). Asked whether the platform’s bosses had been receptive to engaging with the NSPCC, Wanless said they had been “up to a point” – but that it seemed “very reactive”.

Wanless added that it felt as though social media firms had been “slow on the uptake. And that’s about misplaced priorities. It’s not that they’re deliberately setting out to be dangerous to children, but they’ve got other imperatives, like innovating to be the cutting edge of the latest service, and making some money, and ensuring that people stay on their platforms and their products for longer and longer so they can sell more advertising, or whatever it might be.”

Rather than legislating to ban social media, he said he’d like to see proper enforcement of the new online safety laws – and platforms complying with their own terms and conditions. They currently prohibit under-13s, but Wanless said this wasn’t well policed. By contrast, kicking older children off social media “takes the onus off the companies to design with legal enforcement, the duty of care, the guardrails, which they themselves say that they are really keen to do”, he said.

Wanless, who was previously a civil servant and worked as private secretary to former PM John Major and Tory MP Michael Portillo, leaves the NSPCC on 7 December and will be replaced by outgoing RSPCA boss Chris Sherwood.

He said he was “proud of the strategy and where we’ve positioned ourselves”, but during his time at the charity he’d realised how most people in Britain have “no bloody clue” about the reality of life for many children – “growing up, seven or eight, in a high-rise flat with not enough food” – and that there were still “so many things which could be better”.

Among the priorities for the new government should be banning smacking in England. While it’s illegal for a parent to hit a child in many other countries, including Scotland and Wales, in England there’s still an exception for “reasonable punishment” – a fact Wanless described as “morally repugnant”.

He said it was “encouraging” that the Department for Education was considering a ban. “I think there’s still some politicians who get a bit anxious about it – you know: ‘I was [smacked] when I was a kid. It never did me any harm.’ But the Sara Sharif case, I think, has reminded people this is intolerable,” he said.

Wanless added that while he was hopeful that improvements under the new government, he was “also quite cynical”. After Labour was elected, there was a “big reception at Downing Street, which was a kind of love-in”, he said. “But if the indicators still go in the wrong direction … we’ve got a problem. So the jury’s out.”