My grandfather Brian Worth, who has died aged 84, was deputy assistant commissioner of the Metropolitan Police and head of CID operations at Scotland Yard – at the time the youngest man to have reached that rank. In his CID role he led the investigation into the Brink’s-Mat robbery in 1983 and in earlier years was part of the team investigating the Rolls Razor fraud case in 1968.

In charge of all the detectives in London, he was also responsible for creating the Met’s kidnapping protocol and was a liaison officer for Interpol and the FBI, flying to the US a number of times throughout his career.

Born in Doublebois, Cornwall, to Frederick Worth, a railway signalman, and his wife, Ellen (nee Hayne), a domestic servant, Brian went to King Edward VI grammar school in Totnes, Devon, the town where he grew up and where he met his wife, Daphne (nee Bully), when they were both aged 17.

After national service in the RAF he moved to London and joined the Met, starting as a probationary constable and rising quickly through the ranks. At various points he was in charge of police stations in Chelsea, Notting Hill and Brixton, among others, and he held all sorts of posts – including as detective, inspector, chief inspector, superintendent and chief superintendent – on his way to becoming deputy assistant commissioner in 1982. A trained negotiator for hostage situations, he worked on many high profile cases, although he was unable to talk to us in detail about many of them.

When he retired from policing aged 54, Brian was appointed OBE – “not bad for a country lad born in railway cottages,” he used to joke – and moved with Daphne, who was a primary school deputy head, to Torquay in Devon.

A playful, witty and generous man, he then became a somewhat unlikely television star, appearing alongside Paul Ross on ITV’s Crime Monthly series for five years from 1989 and with his own segment, Brian Worth’s Casebook, which looked at famous old criminal cases.

Following my family’s relocation to France in 2002, he and Daphne soon followed, and they lived near to us in the Charente region just outside Angoulême.

He is survived by Daphne, and their daughter, Deborah, and granddaughters, Thea, Clemency and me.