His death – intolerably sudden, as it was – left friends stunned and shocked, and his wife, Lady Gabriella Windsor, heartbroken.

But now, 14 months later, more light can be shed on the scale and scope of Thomas Kingston’s business ambitions and perhaps also on some of the pressures that the 45-year-old former hostage negotiator was contending with.

After serving in the Foreign Office – notably in Baghdad, during the worst years of the Iraq War when he inspired a colleague to describe him as ‘one of the most remarkable people I have ever worked with’ – Kingston plunged into the financial world.

By 2017 – two years before his marriage to Prince and Princess Michael of Kent’s daughter Ella, 44, in the presence of Queen Elizabeth and Prince Philip – he became a director of Devonport Capital, which specialises in providing finance for companies involved in post-war reconstruction.

The company, of which Kingston was joint owner, has now been put into administration. A preliminary statement shows that Devonport Capital owes creditors a staggering £29.5million.

Kingston and his fellow director and joint owner, Paul Bailey, had secured the backing of New Zealand-born billionaire Christopher Chandler, who helped finance the television channel GB News.

Such was Chandler’s faith in the duo that he’d invested millions in Devonport – and is currently owed nearly £13million by the company.

His Majesty’s Revenue & Customs is owed £788,000, though that’s dwarfed by the £1.67million which Devonport owed to another of Kingston’s companies, Aberdair Ltd.

Thomas Kingston with his wife Lady Gabriella Windsor Kingston. The couple married in May 2019

The pair at Royal Ascot in 2023. At the inquest into Thomas’s death, it emerged that he had struggled with depression and had been taking selective serotonin reuptake inhibitors (SSRIs) as anti-depressants – but had stopped taking them.

Tom’s father, the eminent barrister Martin Kingston, is personally owed £162,000.

All of this might suggest that Kingston had been overwhelmed by a sea of debt. But that would appear to be inaccurate: Devonport was, and is, in a position to return all money to investors and creditors – and still have a £2.5million surplus.

‘In February 2024, the decision was taken to wind down the business of Devonport Capital,’ a spokesman tells me. ‘Having made significant progress realising and securing funds, it became clear earlier this year that the best way to ensure fair and proper allocation of outstanding recoveries was to place the business into administration.’

But perhaps in his last days Kingston had, tragically, lost sight of this. At the inquest into his death, it emerged that he had struggled with depression and had been taking selective serotonin reuptake inhibitors (SSRIs) as anti-depressants – but had stopped taking them.

His wife, in a statement read out on her behalf, said: ‘[Work] was certainly a challenge for him over the years, but I highly doubt it would have led him to take his own life, and it seemed much improved. If anything had been troubling him, I’m positive that he would have shared that he was struggling severely. The fact that he took his life at the home of his beloved parents suggests the decision was the result of a sudden impulse.’

The coroner ruled that Thomas was suffering adverse effects of medication prescribed by his doctor.

This prompted his parents to call for a change in how SSRIs are prescribed, with his father making an appearance on Radio 4’s Today programme. Patients, he argued, should be told explicitly about the potential side effects of the medication – including the possible consequences if they stop taking it.