East Germany's secret police, the Stasi, knew Dr Robin Pearson by his codename Armin, according to the BBC Two series, The Spying Game.

But to the staff and students at Hull University - and his neighbours nearby - Dr Pearson, 44, is a respected senior lecturer and author in economics and social history.

His current teaching includes Germany from 1806 to 1850 and popular protest and the question of class struggle in Britain 1815-1835.

He is said to be working on a book called Fire Insurance and the British Economy 1700-1850.

But even if that sets the best-seller lists alight, it is unlikely to propel him into the limelight as quickly as the reports of his 12 years a spy.

Dr Pearson: From The Spying Game to the fame game

According to The Spying Game, Dr Pearson's espionage career began in 1977 in Edinburgh where he took his degree in German and history and later a Masters.

It was while he was there that his undergraduate course took him to Leipzig for a year.

Stasi recruiters viewed Dr Pearson as a possible agent from the moment he arrived at the city's university.

His spy contact, Berhart Kartheus, told the programme that Dr Pearson, who became involved in the communist youth movement, "just felt right from the first time we met... Robin is not the type to do this kind of work for money".

By 1978, and back in Edinburgh, it was claimed Dr Pearson began spying on his fellow British students - reading their dissertations and looking for clues to their politics, as well as supplying the names of former students who got sensitive jobs at Nato and the Ministry of Defence.

David Rose, the BBC journalist who investigated Dr Pearson, said: "Thanks to Dr Pearson, the Stasi had names of young people working in these jobs who could then be targets for the communist secret service."

Fencing cover

From Edinburgh, he moved to Leeds University to do a doctorate in German economic history.

It was there that it is claimed Dr Pearson, an expert fencer, used matches abroad as cover for meetings with his handlers.

Bernhard Kartheus was Dr Pearson's handler

The Stasi wanted to know if academics in the Leeds University Russian department had links with British intelligence, and the information he obtained was important enough for the Stasi to pass to the KGB, the BBC said.

In the early 1980s, Dr Pearson helped the Stasi and their colleagues in the Polish intelligence service, who were trying to unearth supporters of the renegade Solidarity trade union movement.

In autumn 1982, he took a job in London where the Stasi is alleged to have asked him to get to know women at the Ministry of Defence.

He arrived in Hull in 1985, four years before his spying days are said to have ended with the collapse of the Berlin Wall and the end of the East German state.

However, according to intelligence expert Anthony Glees, Dr Pearson would have been highly regarded by the Stasi.

He said: "It is quite clear that he was regarded as a long-term bet, alongside Kim Philby and had the Berlin Wall not fallen, he undoubtedly would have been in a position to have done great harm and to have put many people in harm's way."