So how did a Sunderland lad end up rubbing shoulders with Russian oligarchs?

After attending Aberystwyth University and enjoying a successful career working for legal firms in London, Stephen Curtis’s commercial and property law company began to establish itself in the capital at the same time as the end of the Cold War had triggered the privatisation of the Russian oil industry in the early 1990s.

This led to his business working for Bank Menatep, which looked after much of the new tycoons’ wealth, and Siberian oil company Yukos.

As the oligarchs began investing their roubles in the London property market, so Curtis and Co’s reputation began to grow at its Mayfair offices.

Clients included oil and media magnate Boris Berezovsky, later found dead at the age of 67 in the bathroom of his Ascot mansion, who sought sanctuary in England after facing embezzlement accusations in Russia.

While Mr Curtis’s own fortunes blossomed to the extent that he could buy 19th-Century Pennsylvania Castle, near Portland, Dorset, he had reportedly started to fear for his life at the start of 2004.

At 6.59pm on March 3, his £1.5million Agusta helicopter left Battersea Heliport, in London, for home.

Approaching Bournemouth Airport, the runway was obscured by sudden cloud and both Mr Curtis and pilot Max Radford, 34, died instantly when the craft crashed into a nearby field.

Despite evidence from his uncle, Eric Jenkins, about Mr Curtis’s fears for his safety, an inquest jury decided in 2005 that the crash was caused by pilot disorientation during bad weather.

After learning that separate police and air accident inquiries had ruled out foul play, they took an hour to reach their conclusion.

Thirteen years on and their verdict may soon be challenged as part of a far wider investigation with global implications.