Nicholas Goddard, a respected chemical engineering lecturer at the University of Manchester, was revealed to be living a double life as an adult film actor after a student recognised him in a film

The university professor who was unmasked as a porn star working under the stage name 'Old Nick' after he was spotted has resigned from his job.

Nicholas Goddard, a respected chemical engineering lecturer at the University of Manchester, was revealed to be living a double life as an adult film actor after a student recognised him in a film.

Although the university initially suspended the divorced father-of-three, whose academic career spans almost 35 years, while they investigated the matter it emerged today that Professor Goddard has now formally resigned.

It emerged last week that millions of people across the world have watched the lecturer perform as Old Nick in dozens of pornographic films which he recorded while working at the university.

But his career moonlighting as a porn star only came to light when a student recognised him in one of his films.

Another of his students wrote online: ''The day I found out, I was doing the afternoon ritual of mine [watching pornography], when I suddenly came across a strange video.

'It seemed like an ordinary clip, except the guy appeared to resemble Nick [Professor Goddard], similar build and hair.

'The first disturbing sign of confirmation was the oddly recognisable voice. Then I saw the video's title, 'Busty teen Lolly ***** Old Nick outdoors'.

'But the realisation came when I noticed all his distinct mannerisms and gestures. It was Nick. For the first few minutes, I couldn't believe my eyes, the very idea was disturbing.

'I had to show it to somebody, to prove it wasn't my mind playing tricks.'

And it was not - for in the video on the world's biggest adult website, PornHub, Professor Goddard can be seen reclining on a rug in a garden, wearing sunglasses and a pair of black underpants. Co-star 'Lolly', a young Russian blonde in a yellow polka-dot bikini, begins to massage him with sun-cream.

Although the university initially suspended the divorced father-of-three, whose academic career spans almost 35 years, while they investigated it emerged today that Professor Goddard has now formally resigned

'You have a very nice body,' the professor tells her. 'I know,' she replies in a heavy Russian accent. You can guess how the eight-minute tale continues.

Professor Goddard revealed last week that he had quit the adult film business in January because it became 'too much'.

A statement released by bosses today said: 'Professor Nick Goddard has resigned from his position at the university with effect from April 1, 2016.

'His teaching and supervision duties will be undertaken by other colleagues between now and April 1, 2016.'

Professor Goddard married in 1981, a few years after graduating from Oxford. The son of a clerk at the old Ministry of Labour (which became the Department of Employment), he had three children with wife Christina. The couple were together for 25 years, until they separated in 2006.

University of Manchester chemical engineering professor Nicholas Goddard is seen here in one of the films

His family was apparently unaware of his other job, which involved him having sex with dozens of women - often wearing only a gold watch. He is believed to have started his second career following a divorce.

Professor Goddard appears in a number of academic videos on the university's website - and has published scores of scientific papers during his career.

He is the lead tutor on three courses, having taught chemical engineering for nearly 25 years.

Professor Goddard said he didn't get paid much during his stint as an adult movie star, but did get travel expenses.