IT is an all too familiar scenario: having a Scottish bank note refused by a trader south of the Border who is suspicious about whether or not it is legal tender.

Now it seems that it isn't just newsagents, bar staff and cabbies who doubt the veracity of a good old-fashioned Scottish note - even cockney gangsters and stick-up men have their doubts. Bruce Reynolds, the mastermind behind the Great Train Robbery, revealed in one of his final interviews that the notorious gang ditched hundreds of pounds of Scottish notes because they too were wary of taking the "foreign" money.

A haul of nearly £2.6 million in used banknotes - around £41m in today's money - was taken during what became known as the crime of the century when a gang of at least 15 men stopped the Glasgow-Euston overnight mail train as it passed through the ­Buckinghamshire countryside close to Cheddington.

The 50th anniversary of the classic crime - which took place on August 8, 1963 - was marked last week.

During their investigation, police found evidence in the gang's hideout at Leatherslade Farm, including mailbags, balaclavas, bolt cutters, instructions for using handcuffs - and a Monopoly board complete with incriminating fingerprints. The gang used the loot as Monopoly money while playing the game.

Inside one bag was a wad of ­Scottish bank notes - totalling £628 - which the robbers had failed to take with them.

Author Nick Russell-Pavier, who carried out a series of interviews with Bruce Reynolds before his death, said the gang member had indicated many of his accomplices were reluctant to take the Scottish notes simply because they were wary of the currency.

A total of £19,692 and 10 shillings in Scottish and Irish notes was contained in the mailbags on the train. Russell-Pavier said: "The whole premise was they were just a bit wary about Scottish notes - in the way some people are even today."

Russell-Pavier interviewed ­Reynolds - who died in February aged 81 - several times in 2010 and 2011.

The author also combed through records such as the Post Office archives in a bid to unravel the "folklore" surrounding the robbery and the subsequent capture of 12 of the gang, who were jailed for a total of over 300 years.

The book, The Great Train Robbery: Crime Of The Century: The Definitive Account, co-authored with Stewart Richards, notes that for the gang to have left behind the mailbags and cash seemed to be an "extraordinarily stupid mistake" and that if the gang had cleared up the evidence at the farm effectively, "none of the mail-train robbers would ever have been successfully prosecuted".

One gang member did take some of the Scottish currency, though, and lived to regret it. Roy John James, the chief getaway driver, was caught after a chase over the rooftops in London and had £131 in cash in his pocket when arrested. Two of the £5 notes were identified as belonging to the National Commercial Bank of Scotland, Inverness, which had been sent to London by registered post via the mail train on August 7, 1963.

Russell-Pavier said James - a racing driver - may have been more "cosmopolitan" than some of his counterparts in the gang.

He added: "One thing in terms of understanding these people as human beings is that they came from a very small closed-in world.

"They were working-class London boys and they didn't really know much about the wider world. Part of the reason they chose to have a country hideout was that, rather naively, as city boys they thought in the country there aren't that many people around.

"But, of course, in rural communities you are much more conspicuous if you are in a farmhouse in the middle of the countryside."

The refusal of traders to take Scottish bank notes - printed by the Royal Bank of Scotland, Bank of Scotland and Clydesdale Bank - has long provoked ire.

There is no legal onus on retailers to accept them.

Last year, London Mayor Boris Johnson instructed the city's buses to take Scottish notes after visitors to the city complained about drivers refusing to take the notes as payment.

In 2009, David Mundell, the Conservative MP for Dumfriesshire, Clydesdale and Tweeddale, tried to put forward a back-bench bill to force retailers to accept the notes by law, but the proposal was rejected.