The father-of-two, from Southsea, Hampshire, told Amrita Sebastian he was worth £6.8million when he first contacted her on the dating app in 2015, Portsmouth Crown Court was told.

Promise of big returns

He persuaded her to pump money into a multimillion-pound biopharmaceutical technology deal with the promise of big returns of around £1.8million.

Robert Bryan, prosecuting, told the court that at one stage Dexter sent Ms Sebastian, an Indian national living in Dubai, a message saying: “I am 32, most of my friends did college and uni, all of them have debts and worries and all earn £40,000 to £60,000.

“I bought a hot air balloon yesterday just because I could.”

The defendant previously pleaded guilty to seven counts of fraud and was convicted at trial for possession of articles for use in fraud and perverting the course of justice.

Setting out the elaborate lies Dexter used to execute his plot, the prosecutor said: “He claimed he was a successful businessman selling biopharma technology and was worth £6.8million.

“He said he was involved in Hollywood studios and he alluded to immense wealth, private jets and expensive cars.”

He added that Dexter claimed to earn more in interest from his investments than a doctor’s annual salary.

The court was told that in October 2015, Dexter persuaded Ms Sebastian to invest in a patent catalogue including a “bioreactor paddle” patent which he falsely claimed to have arranged to sell to medical firm 3M.

Dexter claimed the deal was worth £3.6million and that she could benefit from 50 per cent of this.

Mr Bryan described how Dexter continued to ask Ms Sebastian for further sums to cover administration and legal fees – including when she was “extremely ill” in hospital – until she had invested £141,500.

Ms Sebastian alerted officers in April 2017 after Dexter failed to pay her back any money, telling police: “As Dexter had so much of my money, I felt trapped.”

Pay off debts to friends

Mr Bryan said Dexter spent the money on living expenses and to pay off debts to friends and family as well as for a payment to a classic car company.

He added: “It must have been relatively high living.”

John Lucas, defending, described his client as a “bright man, a charming man” and added: “He is sorry for what he has done. He is a well-educated young man who has made a big error of judgment.”

Dexter, wearing a grey suit and pink tie, told the court: “I am very, very sorry to the point I think about it every day, from the moment I wake up to the moment I go to sleep. I can’t justify myself or what I did.”

He added that he had £200,000 in three cryptocurrencies to pay back his victim and a proceeds of crime act hearing was set by the court to be held on April 7.

Sentencing Dexter to a jail term of four and a half years, Judge Timothy Mousley QC said: “There is little sign of any remorse and certainly, in my judgment, no sign of genuine remorse.

“You never spared a thought for her, you knew about her state of health but continued to take her money from her.

“Dishonesty is a feature of your character, it’s profound, and you are someone who shows no hesitation in resorting to lies with an ease that is almost breathtaking.”