File on 4 Investigates

File on 4 Investigates reveals how surgeons had raised concerns about a faulty replacement knee eight years before its US manufacturer finally decided to withdraw it from use.

Knee replacement surgery is one of the most common operations carried out by the NHS, with over 100,000 procedures carried out each year. It’s a surgical success story - but things can go wrong.

Around 10,000 problematic 'NexGen' knee implants, made by the US medical tech giant Zimmer Biomet, were fitted into UK patients over the past decade or so, until they were withdrawn in 2022.

But File on 4 Investigates exclusively reveals that warnings were given to both the company and the government regulator eight years before the product was recalled.

Reporter Adrian Goldberg talks to patients who had to endure the agony of new corrective surgery and orthopaedic surgeons whose reputations were thrown into doubt.

Reporter: Adrian Goldberg

Image: Deborah Booker following her knee replacement operation in 2016

Psychedelics are having a moment — hailed as miracle cures for depression, PTSD and addiction. But what happens when the trip doesn’t end?

In Trip Shocked, writer and researcher Ed Prideaux takes a hard look at the risks lurking in the psychedelic renaissance. Drawing on his own long-term side effects from LSD, Ed explores a hidden history of harms: from persistent hallucinations and underground support groups to therapy sessions that crossed the line.

As billionaires, biotech firms and media stars race to mainstream psychedelics, are we ignoring inconvenient truths about safety, science and consent?

Producer: Nadia Mehdi

In We Are Not A Conspiracy School, Darryl Morris sets out to meet the people behind HOPE Sussex, a community of home educators founded during the pandemic.

On a sprawling site in the East Sussex countryside, a number of families gather to learn together, away from the mainstream. What’s taught there is contested. The media has called it a “conspiracy school", but the founders say it’s a community centre that encourages critical thinking.

What are people actually doing there? And in a world where shared beliefs have fractured, and more are turning away from the mainstream, why do they feel a community like theirs is needed?

Producer: Louisa Adams

When the parent of a patient in a psychiatric hospital questioned why he couldn’t see CCTV footage of an incident involving his son it led to a series of extraordinary discoveries.

Reporter: Noel Titheradge

Nine in ten people in the UK who buy a car use finance. The sector is the second largest lender to consumers in the UK after mortgages. But the industry is bracing itself for a Supreme Court judgement which could see lenders forced to pay out tens of billions in compensation for selling deals with 'secret' commissions. File on 4 Investigates hears from industry insiders and those who tried to raise the alarm on a scandal that some believe could rival PPI.

Reporter: Helen Catt

A deep-dive into the new generation of get-rich-quick gurus and the social media smoke and mirrors some use to shield themselves from criticism. This investigation uncovers the tactics used by some TikTok landlords and online ‘finfluencers’ who use the promise of property riches to sell advice and training to people hungry to make fast money and break free of the rat race.

Thriving in a largely unregulated social media ecosystem, it highlights the intersection of disinformation, influencer culture and power dynamics, showing how unchecked behaviour has far-reaching implications for society and democracy.

When journalist Will Coldwell wrote a long form article about his investigation into property trainer Samuel Leeds, he had hoped that highlighting some of what he saw as the guru’s hard sell tactics and sharing the stories of some of his unhappy customers might lead to him having to change his methods.

But Samuel Leeds, ever keen to tell his own story, co-opted the article and claimed it as a victory - amplifying his own name and brand further.

The report incorporates a full response from Samuel Leeds - who strenuously denies using hard sell tactics or that he seeks to suppress criticism – and maintains that his methods are legitimate and work for his many happy customers.

This is the story of the immersive power of the influencer ecosystem and the invincibility of the personalities that dominate it. It is a story about the limitations of traditional journalism to cut through the content. It is a story about why this investigation isn’t going to work.

Producer: Louise Orchard

When a Church of England volunteer in Leicester rejected a proposal to go on a date, it started a (sinister) stalking campaign against him. His stalker was a female preacher. As her harassment worsened, her victim pleaded for help to the police and the Church, including to a cleric tipped to be the Church’s next leader. File on 4 Investigates reveals how their mistakes left the victim feeling they had failed to protect him…

High street gambling venues, known as adult gaming centres, promise a safe and sociable experience; the chance to have a chat, a coffee and a flutter, under the supervision of trained staff. And they’re proving to be popular, with an increasing number springing up across the country, some of which are open 24 hours a day.

Reporter: Alastair Fee

Ketamine was designed as an anaesthetic but its use as a recreational drug is growing fast, particularly among young people. It can have life-changing health consequences, yet the use of the drug increased by 85 per cent between 2023 and 2024. Paul Kenyon investigates the ketamine trade and discovers how tonnes of the drug are able to find their way into the UK undetected.

Reporter: Paul Kenyon

Details of organisations offering support and information with addiction are available at bbc.co.uk/actionline

The market where carbon offsets are bought and sold has been projected to grow and grow, as big companies look to prove they can reach net zero. But where achieving reductions in emissions is impossible or expensive, an alternative is to try and arrange for carbon to be taken out of the atmosphere instead. The markets have thrived on linking buyers of carbon offsets - big firms, and even governments - to development projects in poorer countries, where land and labour for tree planting are cheap.

But can these projects be safely verified and measured? Are local communities being exploited to try and make the maths add up? And can the industry afford to admit when a project is underperforming the expectations according to which carbon credits have been sold?

Investigative reporter Max de Haldevang hears from experts and individuals directly involved in high profile carbon offset projects to find out.

CORRECTION:

Producer: Robert Nicholson

A Whistledown production for BBC Radio 4