The man wearing sunglasses entered the the Bank of Scotland in St Georges Cross, Maryhill Road in Glasgow shortly after opening time.

He walked up to the teller and handed over a piece of paper with a printed message on it which said:"I want money. Look at what I am carrying in the waistband of my trousers."

When the bank worker raised his eyes he could see that the man had opened his jacket, and the butt of an automatic pistol was visible.

The man then handed over a briefcase which the terrified teller filled with £2700 in banknotes (worth £30,000 now).

The robber took the case and calmly walked out the bank.

It was 9:45am on Friday April 26, 1974.

The police later showed the teller and a colleague photographs of possible suspects.

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They both picked out the same man - Maurice Swanson.

The following morning he was arrested at his home in nearby Raeberry Street in Maryhill loudly protesting his innocence.

Swanson, who was then in his mid-40s, had been born in Latvia and settled in Scotland after the war.

He was a handsome well-built man, six-foot tall, with blond curly hair.

His brief was the legendary criminal lawyer Joe Beltrami.

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Swanson was charged with bank robbery and initially remanded in custody at Barlinnie Prison in Glasgow to await trial. However, Beltrami managed to get him bail.

At this stage things were not looking good for Swanson who continued to protest his innocence.

At an identification parade in Maryhill Police Office he was picked out by the teller he had robbed and a colleague.

Crucially a third woman who had been standing at a bus stop near the bank also recognised Swanson.

With three eyewitness sightings of Swanson, the case against him looked very strong.

However, Swanson claimed he had a watertight alibi.

At the time of the robbery, he'd been picking up a friends wages from the offices of the then Glasgow Corporation ( now Glasgow City Council) in Brand Street, Kinning Park.

Five workers, three Polish, confirmed that Swanson had been there at 9:30am and hadn't left until 10am.

He had even given one of the witnesses Josef Katarba a lift home.

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Two weeks before the trial at the High Court in Glasgow Swanson told Beltrami, above, that his underworld connections had come up with some interesting information.

They said him the man responsible had no previous convictions and therefore his fingerprints and photograph were not on file.

He was also was much younger and had committed another robbery since.

After each raid he headed for Spain to wait for things to cool down. However, Swanson did not know the robber's name.

Beltrami, who died in 2016, dedicated a chapter to the case in his 1988 autobiography, The Defender.

He wrote: "Although Swanson had convinced me this was a case of mistaken identity, I would not be on the jury.

"Such information that he gave me about the mysterious Mr X was hearsay and no value in court.

"So much would hinge on whether the jury would believe the eyewitnesses or Swanson's five alibis."

When the trial began in August that year at the High Court in Glasgow both tellers were adamant that the man who robbed the bank was Swanson. The bus stop woman also backed up their story.

Sunglasses like the ones used in the robbery had been found in Swanson's house.

While detectives showed the journey from Brand Street to the bank could be done in a matter of minutes The prosecution argued it was perfectly possible for Swanson to have both picked up the wages and then robbed the bank.

When Swanson gave his evidence he continued to protest his innocence.

Josef Katarba confirmed that he had been driven home by Swanson that morning after a night shift.

Another witness Victor Griss also confirmed Swanson's alibii, as did the three others.

However, Beltrami by his own admission had made a rare error. His decision to send officer manager Michael McDonald to speak directly to the five at Brand Street had backfired.

The prosecution argued that he had been there to concoct an alibi not to confirm it and should have done the interviews in his office.

The five witnesses had a poor grasp of English and did not come across well in the witness box.

In fact Beltrami described Katarba in his book as a shifty looking character who could not look anyone in the eye.

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Unfortunately for Swanson the jury agreed and he was was found guilty and given five years in prison.

To make matters worse there were no grounds for an appeal.

Beltrami later said:"It would have also have been the height of folly to appeal the sentence which was far from excessive "At that time a failed appeal could also result in an increase in sentence."

Swanson was destined to serve time for a crime he said he hadn't committed.

However a bizarre twist of fate was about to throw him an unexpected lifeline.

The following year a man appeared at Edinburgh Court Sheriff charged with various bank robberies in Edinburgh and Glasgow.

He asked Beltrami to represent him and said he would be pleading guilty to all five.

Significantly, as a first offender, his fingerprints and photograph were on file for the first time.

The breakthrough came while Beltrami was studying a statement he had given to his investigator Jim Penman.

He noticed a sketch map of the same bank in Maryhill Road which Swanson had been convicted of robbing.

The new client had then written:"My first ever bank robbery took place at the Bank of Scotland, St Georges Cross, Glasgow.

"Like the other ones I passed a note and was handed over £2500."

He mentioned the Maryhill Road raid only after Penman asked him if he had committed any other robberies.

Beltrami quickly realised the young man was talking about the same robbery Swanson had been convicted of.

Could this be the mysterious Mr X Swanson had been told about?

After meeting him for the first time in Saughton jail in Edinburgh Beltrami realised the two men were similar in appearance, though there was a 20 year age gap.

He also feared both clients could have cooked up the story to get Swanson out of jail.

However Mr X said he had never met or heard of the Latvian.

It was decided to have second police identity parade in Saughton Prison involving the two tellers and the new suspect.

However both failed to pick out the man they saw rob the bank.

It was a bitter blow to the any chance of the conviction being quashed.

Ironically Mr X was able to tell police that the second teller was the man who had handed him the money.

It was the first ever case where an identity parade suspect had identified one of the witnesses.

Mr X pled guilty to the other robberies and was sentenced to nine years, but the Maryhill Road robbery was not included in the charges.

However one of the officers involved in the original Swanson case Detective Inspector Sinclair Paterson decided to check every fingerprint which had been recovered from this hold up.

They found Mr X's palm print on the revolving door of the bank which proved he had been there at the time of the robbery As a result of the new evidence the detective contacted the Solicitor General for Scotland John McCluskey who was familiar with the case.

In an unusual move it was decided to give Swanson a royal pardon - the first in Scotland that century - which was signed by the Queen on July 23, 1975.

Swanson also received £5,000 compensation ( £40,000 now) for the time spent in prison which had turned his hair white.

In The Defencer Beltrami said Swanston never appeared in court ever again.

Beltrami however declined to reveal the identity of Mr X.

Several years after the Bank of Scotland robbery alibi witness Katarba was stabbed to death in a flat in Glasgow.

Ironically Beltrami represented the woman charged with his murder and she was cleared on grounds of self defence.

Reflecting on the groundbreaking Swanson case, one of only two Royal Pardons in the 20th century Beltrami later wrote:"This was one occasion when the law was not afraid to admit it had made an error."