A new search has begun for the remains of Muriel McKay, who was abducted and murdered more than 54 years ago in the UK’s first kidnap for ransom case.

Mrs McKay, 55, was held to ransom for £1m at a farm in Hertfordshire by a pair who had mistaken her for Anna Murdoch, the then-wife of newspaper tycoon Rupert Murdoch. Her body has never been found.

Mrs McKay’s daughter Dianne, 84, and grandson, Mark Dyer, persuaded police to carry out a third dig at the farm after making contact with Nizamodeen Hosein, one of two brothers convicted for the crime.

Dianne and her brother Ian McKay said: “This really is our last chance.”

Mrs McKay was married to Rupert Murdoch’s deputy Alick McKay. She was abducted from their home in Wimbledon in December 1969.

Nizamodeen Hosein and his brother, Arthur, were jailed for life in 1970 for her kidnap and murder.

While Arthur died in prison, Nizamodeen was deported to Trinidad and Tobago after serving his sentence.

Mr Dyer and his mother visited him in the Caribbean in January 2024, when he pinpointed a location on the farm where he said the body was buried.

Mr McKay said although he did not trust everything Hosein had told his family, “I believe what he’s saying about where my mother’s body is”.

“He knows exactly the spot he buried her in.

“I’m prepared for anything, but this is really our last chance,” he added.

Officers searched Stocking Farm in Stocking Pelham at the time of the murder and again in 2022, with the help of ground-penetrating radar and specialist forensic archaeologists. Nothing new was found.

A Met Police investigation team flew out to interview Hosein in March.

Despite “concerns about inconsistencies” in his account, they said detectives would carry out a final dig starting on 15 July “for completeness”.

Cdr Steve Clayman said their inquiries “highlighted other areas of potential interest”, including where a manure heap once stood.

“We know now this was probably larger than we previously thought and therefore that area was not entirely searched in 2022.

“We all share a hope and desire to find Muriel’s remains and bring some closure to her family after all these years,” he added.

Mr Dyer said he would even consider flying Hosein to the farm “if we get nowhere by midweek”.

“I know he’s particularly keen to see this resolved,” he said.

However Mr Dyer added: “To be honest I don’t want him here – if he’s told us the truth – we shouldn’t take that long finding her. It’s a couple of feet either way.”

He said his mother, Dianne, and her siblings would only be invited to Stocking Farm if police found something, at which point the dig would “stop immediately”.

“Nothing would be better for our family than finding the body and taking her away, giving her a proper burial – then the mystery is over, it’s done,” he added.

The farm’s owners previously said: “We agreed to support the decision of the police.

“They have now made their decision, which we respect, although we understand that this was a finely judged call considering the unreliability of the evidence provided by the murderer.”

The police have told Mrs McKay’s family that if the latest search is unsuccessful “it would not be proportionate to carry out any further searches or investigations”.