An elite secret unit of highly trained investigators aimed at rooting out corrupt police and their criminal conspirators. Allegations of misconduct bedevilling a force. And a network of private messaging apps where officers trade shameful information.

No, not the Metropolitan Police – although Commissioner Sir Mark Rowley has been forced to move 90 officers from tackling serious crime and terrorism to investigating their colleagues – but the fictional world of cop-turned-thriller writer Neil Lancaster.

Described by crime writing legend Ian Rankin as “Jack Reacher fronting Line Of Duty”, Lancaster’s procedurals – the fourth of which, Blood Runs Cold, is just out – reflect anxiety over who polices the police.

Published in September 2021, Dead Man’s Grave which kicked off the gripping series predated many of the current scandals.

But there’s no escaping the timeliness of Lancaster’s DS Max Craigie and his fictional Police Scotland team – nor their broad appeal in the wake of hit TV dramas like Line Of Duty, Happy Valley and Grace.

Featuring bent community cops selling information for sexual favours, brutal Albanian gangsters trafficking drugs and women, and murder at the highest levels of law enforcement, you might think his latest yarn is stretching credulity.

Until, that is, you pick up a newspaper or turn on the television news for the latest claims against Britain’s biggest police force.

Despite a reforming new commissioner, the Met Police is neck-deep in its worst corruption crisis since the seventies amid the widespread bungling of sexual and domestic abuse claims against serving officers.

Ex-officers Wayne Couzens, who abducted and murdered 33-year-old Sarah Everard, and serial rapist David Carrick, jailed over a 17-year campaign of terror against women, have shattered public trust.

Other cops have been sacked recently for sharing vile racist, sexist and misogynist WhatsApp messages, crime scene photos, and abuse aimed at model Katie Price’s son Harvey, who has learning difficulties.

Sir Mark, who came out of retirement to become commissioner six months ago, has vowed to “lift the stone” and insisted the majority of officers backed his efforts.

“The most urgent thing is to remove the cancer from the body,” he added.

Ex-detective sergeant Lancaster, 57, who retired from the Met in 2015 after 25 years’ service, including many years as a covert policing specialist, agrees wholeheartedly.

“I’m proud of the fact I was a Met officer and I think my account balance is in credit,” he states firmly.

“But it’s become an open wound and the plaster needs to be ripped off. I’ve got friends and family in the police and it’s really hard for them. It’s a very difficult time. Things are changing – and much needs to change – but good cops hate having criminals in the ranks as much as everyone else.”

Born in Liverpool, a primary school contemporary of Strictly Come Dancing star Anton Du Beke, the father of three now lives in the Scottish Highlands.

He is commendably reluctant to be cast in the role of armchair expert, or be seen to be exploiting crime victims or his ex-force for publicity.

Yet before joining the Met, he spent six years in the RAF Police and his experience of ‘The Job’ shines through.

Today, he fears for the relationship between police and public.

Low morale, poor-quality recruits, insufficient vetting and non-residential training have all played their part, says Lancaster, but he also blames the closure of police stations, and hands-off management.

Police “canteen culture” was a term once used to describe the toxic coteries in which misogynists like Wayne Couzens could hide in plain sight, but Lancaster suggests a “counter argument”.

“When we had canteens in the Met, you’d come in to have a meal and decompress. You’d be with senior officers, admin staff, visitors. You could share ideas and let off steam,” he explains carefully.

“Now they’ve gone and officers have to eat where they can, often on the go. There’s a disconnect. Where it the time to decompress?”

The rise of social media and smartphones – which you end up on instead – has also contributed to a toxic culture.

“Officers in WhatsApp groups with Wayne Couzens deserve everything they get – the comments were shocking,” Lancaster continues. “But you only have to look at Twitter to see how decent, right-thinking people say the most ridiculous things.”

“Look at issues like trans rights or Scottish independence, and normal folk go from disagreeing to ‘I hate you, you’re a scumbag, you deserve to die’ in moments.” Overall, officers need more interaction, both with the public and their colleagues, he argues.

But perhaps the most pressing issue, he says, is volume of numbers. Some 20,000 officers were lost as a result of austerity measures and the service has never recovered.

“There are not enough staff, full stop,” says Lancaster. “The police are run ragged. Many response teams are also carrying case loads they never get a chance to deal with.”

One ugly example, of which much has been made, is that on February 27, 2021, six days before kidnaping, raping and murdering Sarah Everard, firearms officer Couzens exposed himself at a drive-through restaurant.

It would later emerge this was the fourth (known) time he had exposed himself, with police taking no previous action, leaving Couzens to continue serving with the Parliamentary and Diplomatic Protection branch.

This time they did react, though reportedly did not visit the restaurant where the complaint had been made until March 3 – the day Couzens kidnapped Sarah.

“That case would have been allocated but the officer might not have been on duty, they might have been in court, or sat on permanent watch in a custody suite,” explains Lancaster.

“There’s an argument indecent exposure should be elevated to the status of a really serious crime because suspects go on to commit far worse. But there are too few officers and too much work, and often it’s not police work – something like 60 percent of police time is dealing with mental health crises and missing persons. That means when someone’s burgled, there’s no one to send.”

It’s not just the Met either.

Earlier this month, it was revealed officers across the country failed to visit the scene of 45,233 burglaries in 2022. Data from 19 forces also revealed 75% of burglary cases were closed without a single suspect being investigated.

Lancaster, who will be appearing at this year’s 20th anniversary Theakston Old Peculier Crime Writing Festival in Harrogate, North Yorkshire, continues: “Since 2010, 126 police stations in London have closed.

“Some were quite small – one I served in for many years, Willesden Green, was like a little house – but someone was on duty 24 hours a day.

“If you wanted to talk to the police, you could walk in. Many of these stations have since shut, with officers shifted into super stations.”

“People feel the police have abandoned them and that leads to loss of confidence. What the average person wants if they fall victim to crime is for the police to turn up… and that’s just not happening.”

The author suggests several areas where changes can be made: including recruitment, vetting and management. “We’ve been in a long period of full employment so the police have gone from being able to pick the best candidates to having to take those they can get,” he continues.

“We’ve also seen a change in the actual process. When I applied, you’d be visited at home by a sergeant. They’d chat to you for an hour and get the measure of you. That was incredibly valuable.”

“Now everything’s been outsourced – especially during the pandemic – and there have been cases where the first time a recruit has met anyone from the service has been on their first day as a police officer. Because of this, you’re getting a different calibre of recruit.”

“I don’t want to generalise because there are many great people still serving in the Met, but they’re also getting recruits who wouldn’t have made the standard before.”

Lancaster turned to writing after retiring and has clearly found his forte, having published seven books, including the latest, since 2019. “I enjoyed creative writing at school,” he says. “When I left the police, I found myself with not a great deal of work and living in this remote area and I just wondered if I could write. It turned out I could. I wrote three in an action-adventure series and then came up with Max Craigie.”

Like Lancaster, Craigie is also ex-Forces. He served in Afghanistan and saw a close friend die.

He suffers from PTSD, which he manages through exercise and not drinking.

None of this is based on the author, though he does admit his new book takes inspiration from a real-life trafficking gang he hunted while seconded to an Immigration Crime Team at the Home Office.

Albanian women were being brought into the UK via Eurostar, then disappearing into the underground, and most likely end up exploited.

Thanks to the efforts of Lancaster and colleagues, three men were jailed for a total of 21 years and he was commended.

Today, while the real police might be in the dog house, we’re reading more crime fiction than ever. Lancaster’s books alone have sold more than 200,000 copies.

“I’m not putting on rose-tinted glasses,” he adds.

“The theme of my books is corruption but, just like the real world, it’s good cops catching bad ones. The investigation into Wayne Couzens – led by a woman, incidentally – was praised by the judge as the ‘most impressive police investigation in 30 years’.

“Despite what’s been happening in the real world, our fascination with crime is not going anywhere. People still want to read about the police and watch TV crime dramas – it helps them make sense of a complicated world.”

• Blood Runs Cold by Neil Lancaster (HQ, £14.99) is out now. Visit expressbookshop.com or call 020 3176 3832. Free UK P&P on orders over £20. The Theakston Old Peculier Crime Writing Festival takes place July 20-23. Tickets are on sale from May 2. Visit Harrogateinternational festivals.com for more informationm