It was about 4 o鈥檆lock on 14 November 1888 鈥� a Wednesday. The man behind the counter of the spirit store on Glasgow鈥檚 Parliamentary Road was pretty sure of the time. And he remembered the man clearly. About 40 years old, medium height with brown whiskers. He had a 鈥渄issipated appearance鈥� and 鈥渁ppeared to have sore feet鈥�. But it was the brand-new pound note he proffered that aroused the shopkeeper鈥檚 suspicions. The paper was too soft: when he rubbed it between his fingers and thumb, his fingers went right through it. It had to be bad, he said. The man snatched the note and, despite his sore feet, ran off.
This was the second dodgy pound note in two days. The Bank of Scotland was appalled. Three years earlier it had issued a new set of notes incorporating so much chemical cunning that they were impossible to forge. At least, that was the theory.
ALL the banks were worried about this newfangled photography. Banknotes had always been the target of forgers 鈥� but only the most skilled engravers ever got close to a perfect copy. Photography was going to make the counterfeiter鈥檚 life a whole lot easier. Take a picture of the note 鈥� or its component parts 鈥� transfer each negative to a printing stone and print away.
Advertisement
The banks had some defences. They printed in colours that were hard to photograph, such as blue. Some added a series of features in different colours. That wasn鈥檛 enough for the Bank of Scotland. In 1880, the bank called in Alexander Crum Brown, one of Scotland鈥檚 most eminent chemists. His job was to find a foolproof way to foil the forger.
For three-and-a-half years, Crum Brown and his assistant John Gibson experimented in their lab at the University of Edinburgh. First they turned forger themselves. Notes printed in black on white posed no problem at all. Blue was harder to photograph 鈥� but a yellow filter improved the image. The real challenge was to forge a note from rival bank, the Royal Bank of Scotland. Its notes were the best protected of the time and bore a whole set of security devices printed in red, blue and black and all overlying a finely engraved wiggly pattern printed in yellow. But, as Crum Brown proved, even these ingenious notes were not beyond the skills of 鈥渁 trained chemist who turned his attention to forgery鈥�.
The trick was to isolate each coloured symbol by removing all others, photograph it and transfer the negative to a printing stone. 鈥淲hat photography alone cannot do, may be done by photography aided by chemical treatment of the note,鈥� Crum Brown told the bank.
First they needed an image of the wiggly yellow pattern. They simply photographed a small portion of the note that bore nothing but yellow wiggles and printed it repeatedly over a suitable area of paper. Then they dunked the note in a solution that bleached out the yellow, leaving just blue, black and red. To capture an image of the blue feature, they bathed the note in a sequence of chemicals 鈥� a dip in dilute acid, followed by the addition of hydrogen sulphide and then a metallic salt. 鈥淓very delicacy of the original device remains in black instead of blue.鈥� Black was easy to photograph.
Now they dissolved away the blue to leave just the red and black, and as the two colours didn鈥檛 overlap Crum Brown covered each in turn and photographed the other. Four negatives on four stones, which could then be printed in the right colours. 鈥淎ll that was needed to complete the note was the signature of the cashier, and a forger would no doubt add that with a pen,鈥� reported Crum Brown.
At this point, he almost gave up. It seemed there was nothing a forger couldn鈥檛 crack. Then he hit on an idea. The chink in a banknote鈥檚 defences was the ink. Because each colour was chemically different, a clever chemist could always find a way to isolate each security feature, by treating the note to remove each colour in turn. But if all the inks were made from the same chemicals, that would be impossible. 鈥淚f now we mix our inks so that exactly the same substances are present in them all, but in different proportions our methods of separation will, as a rule, fail because whatever one ink does they all will do.鈥�
Crum Brown picked three pigments 鈥� ultramarine, cadmium yellow and vermilion 鈥� which could be mixed to give a range of colours. He also insisted that each coloured feature should overlap to make things even harder for a potential forger.
The bank commissioned a local artist to design a set of notes along the lines Crum Brown proposed. The pound note was brown, yellow and blue and featured the bank鈥檚 arms, the Arms of Scotland and the Great Seal of Scotland. For added protection, there was a new, improved watermark. When the note was ready, the two chemists did their utmost to forge it. In February 1885 Crum Brown reported back to the bank: 鈥淥ur attempts to copy the note in its final form by chemical and photographic processes have completely failed.鈥�
In May the Bank of Scotland issued its new set of notes. They were, as every newspaper in Scotland reported, impossible to forge.
In November 1888, the first dodgy pound notes turned up 鈥� one at a bank, one at the Glasgow grog shop, and one at a tea room where a little girl ordered fourpence worth of tea and cakes and went home with 19 shillings and eightpence in good, hard cash. The paper wasn鈥檛 as crisp or white as it should have been and all the letters were just slightly different. But the forgery would fool most eyes. 鈥淚t is a finer piece of work than any forgery they have ever seen at the Bank of England,鈥� said George Waterston, the bank鈥檚 printer.
The bank warned its staff. The police alerted shopkeepers. A 拢100 reward was offered for information leading to an arrest. Yet more notes turned up, not just in Glasgow but in Leith, Edinburgh, Kirkwall and Dundee. The reward was increased to 拢250.
In December, the police thought they were onto something. Fake American $20 bills had appeared in Belgium, and the Belgian police were on the trail of an international gang suspected of the crime. One was a dealer in stolen shares. A second had been convicted of passing forged notes in France. This same man had recently ordered a shipment of paper from a London stationer 鈥� the sort used to print banknotes.
In February, the Belgian police finally saw one of the dud pound notes and immediately ruled out a connection. The forged $20 bills had been printed by photolithography. The Scottish pound was the work of an engraver. Everyone agreed that the culprit was a good old-fashioned engraver not a crook with a camera and a chemistry degree. By the summer, 54 forged notes had turned up.
On 24 July, acting on a tip-off from a Miss Elizabeth Rendall, a draper鈥檚 assistant in Edinburgh, the police finally found their forger. John Hamilton Mitchell, aged 74, was an artist, engraver and printer. He had recently fallen on hard times and still had three young children to support. At his home, the police found copper plates, a box of paints, an artist鈥檚 palette and half-finished notes.
Mitchell told the police he had made the notes only to prove he could. 鈥淲ith the last issue of the Bank of Scotland 拢1 note there appeared several articles or paragraphs in the newspapers as to the impossibility of forging the notes. Having a natural propensity to overcome anything difficult in my trade, I was induced by that propensity to try.鈥�
Mitchell was jailed for seven years. Miss Rendall collected her 拢250. And Crum Brown鈥檚 reputation remained intact. His banknotes were still safe from clever counterfeiters with cameras.