Pinkerton: The Scot who saved a president

• An artists' impression of Lincoln's arrival in Washington DC in 1861, flanked by Pinkerton and his bodyguard Ward Hill Lamon

EVENTFUL is one way to describe the multifaceted life of Allan Pinkerton. At least. It was also adventurous, enterprising, worthy, and packed with the spice of variety and danger. For he was truly a man of many parts, this complex Glaswegian who founded the still-going Pinkerton detective agency – which gave rise to the phrase "private eye", because its logo depicts a large, open eye above the words "We Never Sleep".

When he hired his agents, Pinkerton warned them that he was a hard man who ran his company with an iron hand. "I am self-willed and obstinate," he said. "I must have my own way of doing things."

But he wasn't as simple as that. At various points in his colourful life this carrot-haired policeman's son was seen as a drunkard, a defender of truth and liberty, a left-wing troublemaker, a bosses' puppet, a patriot, a traitor, a fugitive from the law, a dogged pursuer of America's most wanted outlaws, a romantic adventurer, a slave saviour, a hard-headed businessman, and a soft-hearted idealist.

"Myth, legend, distortion of the truth and controversy would surround Allan all the days of his life," according to Scottish biographer James Mackay. And American writer Judith Josephson, who also wrote a book about Pinkerton, called him "a maverick who helped shape the meaning of the word 'detective' … one of the most colourful men of the 19th century".

Pinkerton, who grew up in the Gorbals earlier in that century, would one day save the life of America's most legendary president.

That happened 150 years ago this month (23 Feb). But how had he found himself in a position to know of an assassination plot against president-elect Abraham Lincoln, due for inauguration the following month? More pertinent, how had Pinkerton, then 41, travelled so far as to achieve exclusive access, in his heavy Glasgow accent, to the great man's ear?

Pinkerton's leaving of Scotland was like an escape. When he and his Edinburgh-born bride, singer Joan Carfrae, were smuggled aboard a Canada-bound ship three weeks after they were married in March 1842, Pinkerton was a fugitive, having learned he was on the King's Warrant list and soldiers were on their way to arrest him.

A cooper by trade from the age of 12, four years after his father's death, he had become not just an expert barrel-maker but also a passionate orator as a fighter for universal suffrage and a militant member of the Chartist movement that championed "freedom" for the working classes.

The authorities had formed their dim view of him when, at 23, he started to advocate physical conflict in speeches to men on the cooperage floor. While they failed to foil his escape, big waves almost did it for them when his ship was blown 200 miles off course in a storm, to founder on a reef off Nova Scotia.

That was the dramatic beginning of a long string of North American exploits. The sea-soaked Pinkertons were lucky to survive after abandoning ship and being relieved of their valuables by natives.

On their rescue vessel, with only a few coins left in Allan's waistcoat pocket, they determined to test their luck and changed their plan of settling in Quebec in favour of the USA – specifically fast-growing Chicago, where there had to be big demand for his trade skills in an age when everything was transported by barrel. In a remarkably short time, he had his own ten-man cooperage.

It was the next chapter in his life that was to prove catalytic for his career, making his story a remarkably romantic one for writers and film-makers – even if with his gruff, thick-set dark-suited looks, with a bushy beard and flat bowler hat, he had only one only asset as a potential cinematic hero: cool, penetrating blue-grey eyes.

At time of writing, the Paisley-born film star Gerard Butler is set to start executive-producing (and perhaps starring in) a ten-hour TV series about his famous fellow Scot, scheduled for release next year. He is being uncharacteristically coy about the project, however, with his manager Alan Siegel saying merely: "We haven't closed our deal so it's a bit too early to have Mr Butler comment on Allan Pinkerton."

But Butler's colleague-producer on the project, Bob Cochran, said: "Pinkerton was an amazing guy – he took part in all the great sweeping events of the 19th century." At one point, Pinkerton was a key player in the Underground Railroad, a network of secret routes that smuggled slaves to freedom in Canada. Cochran adds: "On one hand he was enforcing the law, and on the other he was breaking it. He was interested in (his own perception of] right and wrong, not so much in the law."

Having grown up with the law at home – his father was a policeman – it was perhaps an inherited suspicious mind that set his second career on track. In 1846, he made a boat trip to a small, supposedly uninhabited island in the Fox River, several miles from his factory, to cut saplings for barrel hoops.

There he noticed a newish path from the shore where undergrowth was bent back. He followed it out of curiosity – and found signs of a recent campsite and fire. What was going on? After informing the local sheriff, he was deputised to help check out the case, and both men crouched in the bushes for five nights to keep watch on the site.

On the fifth they were rewarded with a stunning coup as they arrested, at gunpoint, a 12-strong gang carrying spades and sacks full of the kind of counterfeit dollars that had been spreading uncontrollably around northern Illinois. Impressed by his success and courage in this case, local businessmen hired Pinkerton to seek out more forgers – which he did with some relish – and so the first private eye was born.

Realising that he could make serious money in the challenging business of crook-catching, Pinkerton was hooked. As his reputation for detection grew, he literally rolled out the barrels and moved his family to a more central area of Chicago to accommodate more case-solving offers.

The Treasury Department and the Cook County Sheriff's Department asked him to find the kidnappers of two Michigan girls, and he tracked down and shot one of the abductors, adding a "biggie" to his toll of arrests in 1848 and confirming him in deputy sheriff role. He also became Chicago's first police detective in 1850.

He kept taking freelance commissions, and business was so good that by that year's end he had set up the North-Western Police Agency – later renamed Pinkerton National Detective Agency. Choosing only the best, morally upstanding agents, employing guile and cleverness – and the first female private eye Kate Warne who could get into places male agents couldn't – the agency's tenacity became legendary among the criminal fraternity who began to quake in their boots when they heard they were on its target list.

Stephen Grant of Grant & McMurtrie, a present-day Scottish private investigator, says of Pinkerton: "He inspired me from a very young age, as I was always aware of my industry being founded by this enterprising Scot. Although his methods have been well overtaken now, he was away ahead of the police work of his time, pioneering techniques like use of mugshots and disguises, shadowing, going undercover, and using code names and female agents."

In the general prevailing atmosphere of lawlessness at the time – with American expansion fuelled by gold- and cash-laden trains pushing across often-hostile open country – the post office and the railroads became the agency's biggest clients, and its main work was hunting down railway thieves such as the ruthless Reno Gang. The agency became famed for its dogged pursuit of not only them (running four members to ground) and many other Wild West legends – notably Jesse James, the Hole in the Wall Gang, the dynamite-happy Butch Cassidy and the Sundance Kid, and the vicious Molly Maguires – who returned the compliment by making Pinkerton their No 1 murder target.

But there were also "security" jobs to be done, some of which must have stretched the principles of the old Chartist firebrand. With investigative work into union activities, he was seen as responsible for keeping unions out of various trades around the Chicago area for years, and 300 of his agents played a critical part in the restraint of protesting workers at the Homestead steel plant of fellow-Scot Andrew Carnegie.

Perhaps the workaholic Pinkerton was just too busy building his booming business to appreciate the irony of such matters; for another security job, the biggest imaginable, was in the pipeline, won at least in part by his abolitionist sympathies. These, and his successes, had drawn him to the attention of president-elect Abraham Lincoln, who then hired his agency for bodyguard services. Just as well. For what then transpired was, without doubt, Pinkerton's finest hour.

Despite being relatively moderate in his anti-slavery position, Lincoln's election to the presidency had ripped the country apart. The sympathising North looked on askance as the affronted slave states of the Deep South seceded from the Union like falling leaves.

As the Civil War boiled up, bosses of the Philadelphia, Wilmington & Baltimore Railroad called Pinkerton in to investigate rumours that secessionists were planning to blow up train ferries, rail-lines and bridges on the Susquehanna River. In response, the detective disguised himself, adopted a southern accent, and insinuated his way into the company of the suspects – members of the Plug-Uglies gang, who had terrorised Baltimore, even killing local politicians – and one of them, encouraged to drink too much, revealed in a slip of the tongue that something much bigger was planned.

The plot, thus uncovered by Pinkerton, was to assassinate the president-elect as he stopped to speak in Baltimore on Saturday, 23 February, 1861, on his way from Philadelphia to Washington DC to take his oath of office and deliver his inaugural speech in front of the unfinished Capitol on 4 March.

According to a CIA report, Pinkerton's uncovered intelligence showed that, while secessionists whipped up a riot, a barber who called himself Captain Ferrandini would kill Lincoln, vanish into the mob, and slip away to the South. Baltimore police would have only a small force at the scene, under orders from the mayor and chief of police, both Southern sympathisers.

Certain the plot threat he'd learned of was real, Pinkerton requested an urgent meeting with Lincoln, which was granted. They met at a stop in Chicago, where the detective spoke the heavily accented words that made the politician blench with shock: "We have come to know, Mr Lincoln, and beyond the shadow of a doubt, that there exists a plot to assassinate you. The attempt will be made on your way through Baltimore, the day after tomorrow."

While Lincoln shook his head in shock, Pinkerton insisted that he bypass Baltimore altogether, arriving ahead of schedule in Washington instead. Indeed, the Scot urged the president to allow him to accompany him directly to Washington that very night. But Lincoln felt too obliged to go through with speeches in his next day's schedule. After that, however, he undertook to follow the Scot's advice – changing his travelling times and passing through Baltimore at night.

Also on Pinkerton's advice, just in case there were any attempts on his life awaiting him there too, he disguised himself on arrival in Washington – adopting a hunched-over walk of an old farmer with a cane and a false beard that (in natural form) would later make him so recognisable.

Though such tactics probably saved his life and he went on to make an elegant inaugural speech in front of the Capitol urging a "more perfect union", Lincoln was ridiculed by his enemies for his "undignified" nocturnal trip through Baltimore.

While he was sufficiently stung to express some regret about it later, he was also deeply grateful to Allan Pinkerton, to the extent that, with the Civil War breaking out that same year, he enlisted the Scot's help as a spy against the Confederacy.

True to form, Pinkerton responded well, bringing out valuable information on rebel supplies, defences and conspirators, and becoming known as "The Spy Master of the North". And when he was then appointed head of the Union Intelligence Service, forerunner of the US Secret Service – and in that role was often seen standing shoulder-to-shoulder in the field with his president – he must have allowed himself the occasional moment of quiet pride.

For to have reached that ultimate honour, it had been quite a journey for the poor boy from the Gorbals.

Pinkerton & Jesse James

• Pinkerton and the outlaw Jesse James had an intense dislike of one another. For years, the James gang had managed to outwit the Pinkertons, but on January 5, 1875, Pinkerton's men attacked the home of James' mother, thinking James was inside. The attack resulted in serious injury to Mrs James and left Jesse thirsting for revenge.

• James went to Chicago, the Pinkerton agency's headquarters, vowing to kill Pinkerton. For four months, the outlaw walked the streets of the city with a loaded gun. Inside the gun was a bullet with the name "Pinkerton" written on it.

• The detective did not know James was in the city, but James never carried out his threat.