The Violent Crime Task Force had been set up by the Prime Minister, in conjunction with the Mayor of London and the Commissioner of the Metropolitan Police, to curtail the knife crime epidemic in the city. The unit worked hand in hand with the specialized Metropolitan Police units, fighting Serious and Organized Crime. Knife crime was directly linked to one of their top priorities, tackling the vast and brutal so-called ‘county lines’ drug-dealing empires, which now had a near monopoly on Class-A drugs throughout the UK.

‘County lines’ was the generic name given to gangs – or Organized Crime Networks – bringing drugs on a large scale into different regions of the country. Their principal method of operation was to coerce children and vulnerable adults, either through bribery or brutalizing violence, into hiding, storing and distributing drugs, weapons and cash.

These disposable human couriers were equipped with untraceable pay-as-you-go phones – deal ‘lines’ – giving no link back to their direct bosses if they were caught. They would travel, largely by train, often dispatched to different counties, moving quantities of cocaine and heroin to the local county line ‘lieutenants’. These lieutenants would break the drugs down into individual ‘wraps’ for the street dealers, who would regularly carry the drugs in their body cavities.

Much of the current wave of street violence, Grace knew, came from turf wars between county lines gangs. The gangs themselves were modelled on the Mafia structure, with a ruthless capo, known in street parlance as the ‘Diamond’, at the top, and a lieutenant beneath him, known as the ‘county line head’. And like the Mafia, they were highly efficiently run businesses, willing to torture and kill anyone stepping on their toes.

It was a former boss in Sussex, Alison Vosper – then an Assistant Chief Constable, now Deputy Assistant Commissioner of the Met – who had offered him this six-month posting in the role of Acting Commander. He had accepted it, liking the challenge and thinking he might learn a lot from it, which he could apply down in Sussex. And as an added sweetener, it put him on level ranking with his current boss there, ACC Cassian Pewe.

He missed the camaraderie of his team in Sussex, despite being only a few weeks into the posting. But he was determined this unit would make a difference to the appalling murder rate in London.

Earlier this week, Alison Vosper had phoned, sounding him out about extending the posting for another six months, but Grace was not at this moment enthusiastic. The job up here was taking him away from home too much; he’d barely seen his family during the last month. Added to which, back in Sussex he had two separate murder trials coming up of suspects he had arrested, one starting next spring, set down for Lewes Crown Court. He was going to need time to prepare for them.