I thought charming school pal was normal kid studying for A-levels – then he spilled his secret and all hell broke loose

was the fake name adopted by , who — at the age of 30 — covertly returned to take his exams again in a bid to go back to medical school after apparently being booted out.

Putting on a Canadian accent, he posed as the son of a newly deceased travelling opera singer sent to live with his “Gran” in Bearsden, an affluent suburb of Glasgow.

He duped classmates and teachers for two years — some who had passed him in the corridors when he was there legitimately in 1975 — before the plot unravelled.

MacKinnon, who claimed to have a genius IQ of 162 by the age of nine, confessed all to three unsuspecting classmates during a Tenerife holiday in 1995 and soon the story made headlines worldwide.

The incredible fraud is retold in documentary My Old School, which airs tomorrow on BBC Two.

Former pal Nicola Walker, now 44, who was among the teenage trio on the Spanish island break, told The Sun: “Amusingly, when I told my mum after I came back, she said he was the only reason I was allowed to go — because ‘Brandon’ was ‘more mature’.

“It was shocking but the whole thing was quite funny. I’ve never felt resentment or anger towards him. He was a nice person. He did lie but it wasn’t to be horrible and there was nothing dodgy.

“Often people say, ‘How did you not know?’. But we were teenagers, so there was so much other stuff going on in your life. He looked older but we didn’t question it and took it at face value.”

Self-made hell

The documentary features Nicola, plus former classmates including filmmaker . was interviewed but refused to be filmed so his voice is lip-synced by actor Alan Cumming.

MacKinnon says on the programme: “When you have an adversary, the thing you have to do — if you really want to prevail — is the unimaginable.

Do something that is just so out there that no one is even going to dream you are going to think of doing that.”

In the documentary he recalls being “almost in tears” as he walked through the gates of Bearsden Academy for a second stint, due to his “self-made hell”.

He claims he was kicked out of Glasgow University in 1980 by unfor- giving educators who dismissed a sudden sickness that caused him to fail his exams.

For years he worked at a local health spa while applying to other medical schools without success, until his father died, which triggered something within him.

'Significantly older'

He adds: “I was angry . . . I thought, ‘If this is going to have any meaning — his death, his suffering — let it be this. To hell with those guys that have stopped you, get this done’.”

Determined to find a new route into university, he blagged his way into enrolment at Bearsden with references he wrote himself, putting on another accent to pretend to be his own father during phone calls.

In the documentary, pupils recall thinking he was “significantly older”, with one admitting he looked “about 40”.

However, hood- winking classmates wasn’t MacKinnon’s biggest obstacle.

Some of the teachers at the school had taught him before.

Physics tutor Mr Gunn noted that Brandon was “not fresh-faced”, but explained to staff the student had claimed his “face had been slightly burned” in a car accident.

Wearing a fresh perm — fashioned using curlers an hour before school — it was enough to fool everyone.

Brian was a Grade-A student and went on to gain five top marks in his Highers — the equivalent of English A-levels — which landed him a place at Dundee University.

Impressed by his knowledge, the class sex education teacher once remarked “some- times Brandon teaches me biology” — unaware he was actually older than her.

More controversially, MacKinnon was cast in the school production of South Pacific as US Marine Lieutenant Cable, who falls for a local woman on a south east Asian island but but fears his family’s response.

MacKinnon claims to have unwillingly taken the part, which required him to kiss his teenage love interest, played by pupil Valerie, and refused to do it until the performance.

He recalled: “Valerie’s looking at me as if to say, ‘Why won’t you kiss me? What’s wrong with me?’. Maybe she thought I was gay.”

The part made MacKinnon one of the more popular kids in school and soon he would throw house parties for classmates, making them cocktails and teaching them about Eighties music.

Nicola recalls him being “a really nice guy, who would do anything for anyone”, including regularly helping friends with their studies.

The holiday when he finally came clean about his secret was two years into his double life.

Mystery still surrounds whether he confessed or feared his plot had been exposed.

After word of the revelation spread, the world’s media descended on middle-class Bearsden.

The imposter became a regular guest on chat shows.

He faced no criminal charges, but the deceit cost him a place at Dundee Uni, which accused him of a “lack of integrity”.

Now 59, he is yet to return to his studies and is said to have struggled in the years since, living on benefits in a modest Glasgow flat.

Tragically, head Mr MacLeod died just a year after the scandal broke in 1996 following a short illness.

Nicola, who kept in touch with MacKinnon for two years after school, doesn’t believe he did anything wrong and remembers him as a fascinating individual.

She said: “While he didn’t achieve what he wanted, and he lied, he touched our lives in a positive way. I will always wish him the best.”

• My Old School airs tomorrow at 9pm on BBC Two.