Media playback is unsupported on your device Media caption How Joseph Mifsud fits into Trump Russia inquiry

Who connects the FBI investigation into Trump and Russia, the snapping up of British nuclear knowhow and a reality TV star who makes dresses for the UK prime minister?

Step forward, mystery professor Joseph Mifsud of the London Academy of Diplomacy, originally from Malta, who mixed with Britain's foreign secretary and ex-CIA people, but who also helped connect Team Trump with the Russians.

A Newsnight investigation into Mifsud has thrown new light on to the enigmatic don and his circle, who include a Kremlin trusty and a third man, Dr Stephan Roh, a wheeler-dealer who bought a British nuclear firm which suddenly started coining millions of dollars.

Mifsud left a job at the University of Malta under something of a cloud in 2007, then led a new university in Slovenia.

He left that too, disputing claims that he had fiddled expenses worth €39,332 ($48,550 / £34,320). Next stop was the London Academy of Diplomacy in 2013. It was a rum outfit, now bust, linked to the University of East Anglia and then the University of Stirling.

At one conference he was described as "Ambassador Mifsud" but, although he worked for six months in the private office of the Maltese foreign minister, he was never a diplomat.

Mifsud became a selfie king of the diplomatic circuit. Boris Johnson and then Foreign Office minister Tobias Ellwood were photographed with Mifsud - as was the Russian ambassador to London. Mifsud joined a private university in Rome alongside two former Italian foreign ministers.

In Riyadh he worked for a think-tank run by former head of Saudi intelligence Prince Turki al Faisal, introducing an ex-CIA operative at a seminar.

Mifsud had a fiancée based in Ukraine, according to Buzzfeed. The woman says she hasn't seen or heard of the professor for months but she gave birth to their daughter two months ago.

In April 2016 in the run-up to the American election, Trump foreign policy adviser George Papadopoulos says Mifsud told him that the Russians had "dirt" on Hillary Clinton in the form of thousands of emails, according to court documents.

Media playback is unsupported on your device Media caption George Papadopoulos: The Trump adviser who lied to the FBI

That conversation, which Papadopoulos carelessly relayed to an Australian over drinks in a posh London bar, was reported to American officials weeks later when emails hacked from the Democratic Party were leaked.

The exchange reportedly so concerned the FBI that it opened its investigation into alleged Russian interference into the 2016 election and whether the Trump team helped.

Last year Papadopoulos pleaded guilty to lying to the FBI about contacts with people who claimed they could put him in touch with the Russian government.

A former academic colleague described Mifsud as "cunning", part of a "third rate diplomatic community where there is an element of braggadocio".

So maybe he exaggerated his closeness to the Kremlin to impress Papadopoulos, but one source reflected: "It's clear that Mifsud knew something before the world did. And that raises questions."

In April 2016, Mifsud reportedly introduced Papadopoulos via email to Ivan Timofeev, who works for a think tank close to the Russian Ministry of Foreign Affairs.

That same month, Mifsud was in Moscow on a panel run by the Kremlin-backed Valdai Club with Timofeev and the third man, Dr Stephan Roh, a German multi-millionaire.

Mifsud and Roh interlock: in 2014, Roh became a visiting lecturer at the London Academy of Diplomacy. Roh bought Link Campus University, a private institution in Rome where Mifsud was part of the management and Mifsud became a consultant at Roh's legal firm.

Roh and his Russian-born wife, Olga, have homes in Switzerland, Monaco, London and Hong Kong. And then there is a derelict castle in Scotland - buying it made Stephan and Olga the Baron and Baroness of Inchdrewer.

Image copyright Getty Images Image caption Stephan Roh (right) at The Center for Global Dialogue and Cooperation in 2012

Olga was a star in Fox's reality TV show Meet The Russians, in which, surrounded by the trappings of extreme wealth, she purrs: "My family was always achievements orientated."

She's extraordinarily well-connected, running an upmarket fashion company in London's Mayfair. Among her customers is Britain's prime minister. There is a photograph of Theresa May meeting the Queen in an Olga Roh coat.

In 2005 Dr Roh bought Severnvale Nuclear Services Ltd from its one man-band owner, British nuclear scientist Dr John Harbottle. He then invited Dr Harbottle on an all-expenses paid trip to a conference in Moscow.

But the nuclear scientist was alert to the danger that visitors to Moscow can be targeted or even honey-trapped in compromising situations. Dr Harbottle said: "We smelt a rat. It didn't sound as if it would ring true and I decided that I wasn't going to go to this meeting."

Shortly afterwards, he was fired.

Under Dr Harbottle the company's turnover had been £42,000 a year. Within three years under Dr Roh, Severnvale Nuclear, with just two employees, was turning over more than $43m (£24m) a year.

Dr Roh declined to respond to repeated attempts by the BBC to ask him to explain how he had transformed the business.

Professor Mifsud too didn't respond to Newsnight's attempts to contact him, but has always denied that he is a spy.

When approached by Italian newspaper La Repubblica the mystery professor said: "Secret agent! I never got a penny from the Russians: my conscience is clean."

The FBI investigation into whether Team Trump colluded with the Russians continues - but in doing so it has thrust the troubling connections of characters such as Professor Mifsud and Dr Roh into the light.