A police officer who stalked his estranged wife and placed a listening bug in her bedroom has been sent to jail.

Ainsley Francis hounded his wife Barbara and her new partner for about three years, listening to her calls and entering her home when she was out.

Sentencing the 57-year-old former Metropolitan Police officer to three years and nine months, a judge said: “I am used to seeing cases of stalking, but this is frankly breathtaking.”

Francis, of Plains Avenue, Maidstone, admitted stalking involving fear of violence or serious alarm or distress when he was earlier due to stand trial.

Prosecutor Richard Job told Maidstone Crown Court on Friday that the most sinister aspect of the case was when Mrs Francis, who has now reverted to her maiden name of Stokoe, discovered the listening device in the bedroom of her home in Ditton.

Francis was found to have recordings of telephone calls and even of his wife making love to her new partner Anthony Lock.

Francis and Miss Stokoe had been in a relationship since 1988. Before they divorced the proceedings were protracted and acrimonious.

When she started a relationship with Mr Lock in 2014, Francis started sending her messages asking about her movements and appeared outside her home to observe them.

He asked her to send him a “compromising” photo of herself. When she refused, he replied: “Why not, they are on the internet anyway?”

Mr Job said at one stage Francis described the bedding in Mr Lock’s home, although he was not known to have been there.

Francis sent messages which indicated he knew the couple had travelled to both Germany and Ireland.

Miss Stokoe became aware somebody had been in her home while they were in India. The freezer in the garage was switched off and property went missing.

There was further evidence in 2016 that Francis was repeatedly visiting her home when she was not there. When she confronted him, he admitted it.

“I am used to seeing cases of stalking, but this is frankly breathtaking...” - Judge David Griffith-Jones QC

Her divorce solicitors sent him a letter warning him about his behaviour.

Mr Job said the most sinister aspect of the offending was revealed in March last year when the covert recording device was found in Miss Stokoe’s bedroom, in a power socket next to the bed.

Francis had previously encouraged her to plug her mobile phone in next to the bed, which ensured it was close to the bug, which had been bought on eBay. It sent messages to his mobile phone.

After his phone was seized, it was found to contain 187 audio recordings of Miss Stokoe speaking to Mr Lock, making calls and of them having sex. Forty-two of the recordings were on Francis’ computer.

He at first claimed he had installed the bug to prevent the commission of crime.

“It is notable he was a serving police officer and would have plainly known it was not the way to go about it,” said Mr Job.

Judge David Griffith-Jones QC told Edmund Gritt, defending: “It’s high culpability isn’t it? It is an extraordinary story. There is a high degree of planning.”

Mr Gritt conceded the communications were “grinding and oppressive” and a serious intrusion.

Francis had been a police officer for 29 years and received commendations for his bravery. He was left with a serious spinal injury in an accident in the 1990s.

Mr Gritt said Francis’ son had commented: “He has undone all the good work he has done throughout his adult life.”

Passing sentence, Judge Griffith-Jones declared: “It is depressing seeing you sitting there in the dock facing sentence for very serious criminal offences.”

"Things changed for the worst when Miss Stokoe started a new relationship.

“From that moment on you embarked on a calculated course of conduct which on any rational measure was devious and malicious and extraordinary to the point of, frankly, being breathtaking,” he said.

Francis had stated he had lost perspective, but said the judge: “That seems to me to be an understatement and inappropriate sanitisation of what amounted to out and out criminal behaviour driven by some form of twisted jealousy and determination to control, and be seen to control, your estranged wife in her new circumstances.

“I used the word breathtaking. It is an appropriate word to describe your behaviour, of which you should be thoroughly ashamed.

“The full extent of the distress caused is hard for somebody not affected by your behaviour to imagine. Barbara Stokoe says your actions completely changed her life.”

The judge added it was an aggravating feature that Francis was a serving police officer throughout the period of his offending.

“A prison sentence is demanded,” he said. “Nothing less will do.”

An indefinite restraining order was made.