ATM and PIN

Introduction — the Paisley engineer who gave the world its PIN

The four digits you tap into a keypad to draw cash, unlock your SIM card, or confirm a chip-and-PIN purchase were not dreamt up in Silicon Valley, nor in a New York bank vault. They were patented in 1966 by a 28-year-old development engineer from Paisley, working in a Kelvin Hughes lab for Smiths Industries on a problem the British banks were quietly desperate to solve. His name was James Goodfellow.

More than half a century on, every ATM on Earth — some 3 million of them, from Antarctica to the Forbidden City — still uses the verification principle he set down in UK Patent GB1,197,183. Goodfellow's idea has outlived the cash machine itself, spreading to credit and debit cards, building-entry keypads, SIM cards and phone lock screens. He received a £10 bonus for it. This is the real story of the Scot who gave the world its PIN.

Early life and background

James Goodfellow was born on 18 May 1937 in Paisley, Renfrewshire — the proud weaving town whose old boast might as well be its motto: 'Keep your eye on Paisley.' He attended St Mirin's Academy, and on leaving school in the early 1950s he was captivated by the emerging world of electronics and decided there and then to make it his career.

He began as an apprentice at Renfrew Electrical & Radio Engineers, completing his training in 1958, then carried out National Service with the Royal Electrical and Mechanical Engineers (REME), where he designed a mobile electronics workshop to support the Thunderbird surface-to-air missile. In 1961, aged 24, he joined Kelvin Hughes — a division of Smiths Industries Ltd — as a development engineer. The employer detail most often gets muddled: Goodfellow worked for Kelvin Hughes / Smiths Industries; the mechanical cash housing was built by Chubb Lock & Safe; and the bank that triggered the project was Westminster Bank.

The Problem Banks Faced

Britain in the mid-1960s was a country of strict banking hours. Branches closed by mid-afternoon and on Saturdays, which was a genuine hardship for working people who were paid weekly and largely in cash. If you missed the queue before half past three, you waited. If you couldn't make it on Saturday morning, you waited until Monday.

The banks wanted to stop Saturday-morning opening without abandoning their customers. The answer they reached for was a machine that could hand out cash when no human teller was present — a problem that had defeated everyone who had looked at it. The fundamental difficulty was not mechanical. Dispensing notes was the easy part. The hard part was knowing, with no clerk in the room, that the person standing in front of the machine was who they said they were.

The Invention — The ATM and PIN

In 1965 the 28-year-old Goodfellow was handed the project. The deceptively simple brief was: build something that lets a genuine customer — and only a genuine customer — take cash from a machine with no clerk watching.

In his own words: 'My task was to design the means of allowing a customer, and only a genuine customer, to actuate the dispenser mechanism.' He worked through the alternatives — fingerprints, voice recognition, retinal patterns, magnetic stripes, online operation — and found them all unworkable on grounds of cost, bulk, or technical feasibility in 1965. His breakthrough was elegant. He combined something the customer had (a machine-readable encrypted card) with something only the customer knew (a numerical, obscurely related Personal Identification Number entered on a keypad).

That combination — a machine-readable card plus a secret numeric code — is the heart of his claim, because it is exactly how every modern ATM works. The invention is covered by UK Patent No. 1,197,183, application number 19319/66, with a priority date of 2 May 1966, a complete specification dated 25 July 1967, and a publication date of 1 July 1970. It names James Goodfellow as inventor alongside Smiths Industries' general manager A.I.O. Davies, and is also covered by US Patent No. 3,905,461 — which subsequent ATM patents cite as prior art.

The Chubb-built machines that followed read a plastic card punched with about 30 bytes of holes encoding the customer's account and branch. Crucially, the PIN was scrambled relative to the card data, so it could not be read off the card. The customer keyed a PIN — described in the patent as a 'plural-character' code rather than a fixed length — into a keypad; the machine compared the two inputs, and if they matched, out came the cash.

The Rival Claim

On 27 June 1967, more than a year after Goodfellow's filing, the world's first cash machine was ceremonially unveiled at a Barclays branch in Enfield, north London — with comedy actor Reg Varney of On the Buses making the first withdrawal. It was the work of John Shepherd-Barron, managing director of De La Rue Instruments. But the De La Rue Automatic Cash System worked completely differently: customers fed in a single-use paper voucher impregnated with carbon-14, a mildly radioactive isotope the machine detected, then keyed a PIN. There were no plastic cards, and De La Rue deliberately never patented the design.

The honest verdict is this: Shepherd-Barron was first to install a working cash machine; Goodfellow invented and patented the card-and-PIN system that the entire world adopted. When Shepherd-Barron's US patents from 1968–1969 were later challenged, the US Patent Office cited Goodfellow's earlier British patent as prior art and rejected the claims. As Goodfellow himself put it: 'He invented a radioactive device to withdraw money. I invented an automated system with an encrypted card and a pin number, and that's the one that is used around the world today.'

American inventor Luther Simjian's earlier Bankograph was a deposit machine — it photographed cash fed into it but did not dispense cash. Don Wetzel's Docutel 'Docuteller', installed at Chemical Bank in Rockville Centre on 2 September 1969, was the first American ATM and used magnetic-stripe plastic cards. Goodfellow's distinct contribution sits inside all of them: the card-plus-PIN verification system at the core.

Why the PIN Matters More Than the Cash Machine

The cash dispenser was a clever box. The PIN was a universal idea — and it has outgrown the ATM entirely. The Queen Elizabeth Prize for Engineering notes that Goodfellow's original method is still evident in machines worldwide, 'facilitating more than a billion chip-and-PIN sales every day.' From the ATM the concept spread to credit and debit cards, building-entry keypads, SIM cards and mobile-phone lock screens.

Here the article must be careful, because this is where myth has crept in. The famous anecdote — that the PIN was cut from six digits to four because the inventor's wife could only remember four — is true of John Shepherd-Barron, not James Goodfellow. Shepherd-Barron, an army veteran, first proposed a six-figure code based on his army number; his wife Caroline vetoed it. As he told the BBC: 'Over the kitchen table, she said she could only remember four figures, so because of her, four figures became the world standard.' There is no credible evidence that Goodfellow used his wife's birthday or chose four digits for memory reasons — his patent specified only a 'plural-character' PIN, and his own accounts are strictly technical.

Recognition — and Why It Took So Long

Here is the sting. Because Goodfellow was a salaried employee and the patent belonged to his employer, he received a £10 bonus for the invention — around £160 in today's money. He never earned a penny in royalties. He went on to a long and distinguished engineering career at IBM in Greenock, twice winning IBM's Outstanding Technical Achievement Award, and retired in 1992 — for decades almost entirely unknown to the public.

Recognition came late, and largely by accident. When Shepherd-Barron received an OBE in the 2005 New Year Honours, widely reported as 'inventor of the automatic cash dispenser', it stung Goodfellow into action. He dug out his patents, contacted the Patent Office, and made his prior claim public. The following year Goodfellow was appointed OBE in the 2006 Queen's Birthday Honours — reported by The Scotsman as being 'for services to banking as patentor of the personal identification number'. Further honours followed: a John Logie Baird award for outstanding innovation (2009), third place in the Intellectual Property Office's British Visionary Inventor award (2012), an honorary doctorate from the University of the West of Scotland (2014), and induction into the Scottish Engineering Hall of Fame on 7 October 2016, alongside James Clerk Maxwell, Alexander Graham Bell and John Logie Baird.

Legacy

Every ATM on the planet — some 3 million of them — uses the card-and-PIN verification system that James Goodfellow invented. But the PIN's reach goes far beyond the cash machine. Chip-and-PIN cards arrived in the UK through trials from 2003, culminating in the famous Chip and PIN changeover day on 14 February 2006 — Valentine's Day, branded 'I ♥ PIN' and described at the time as the biggest change in UK consumer behaviour since decimalisation.

Contactless payments, introduced in the UK in 2007, still lean on the PIN: you are prompted for it above the contactless limit (raised to £100 in 2021) and periodically as a security reset. According to UK Finance, 19.2 billion contactless card payments were made in 2025 in the UK, with a total value of £311 billion. Add SIM-card PINs and phone passcodes, and Goodfellow's six-decade-old idea is woven through daily life.

It is sometimes claimed the cash machine was voted 'the most popular invention of the 20th century' in a consumer poll. We could find no reputable, named poll substantiating that, and it should be treated as unverified rather than fact. What can be said with confidence is that the ATM is routinely described by the industry as the most-used way for consumers to physically interact with their bank. On the question of a banknote — despite Clydesdale Bank's long tradition of celebrating Scots — James Goodfellow has not appeared on one. A street mural in his native Paisley, painted by a neighbour, stands as a more local tribute.

Frequently Asked Questions

Who invented the PIN? The Personal Identification Number, paired with a machine-readable card, was conceived and patented by Scottish engineer James Goodfellow of Paisley while working at Kelvin Hughes (Smiths Industries) in 1965–1966. UK Patent GB1,197,183 carries a priority date of 2 May 1966.

Who invented the ATM? Credit splits two ways. James Goodfellow invented and patented the card-and-PIN verification system every modern ATM uses (2 May 1966). John Shepherd-Barron of De La Rue installed the first public cash machine at Barclays Enfield on 27 June 1967, but it used a radioactive paper voucher, not a card and PIN.

Why is the PIN four digits? The four-digit standard comes from Shepherd-Barron's Enfield machine — his wife Caroline insisted she could only remember four numbers. Goodfellow's patent specified only a 'plural-character' code, so the famous wife-and-four-digits anecdote belongs to Shepherd-Barron, not Goodfellow.

How much did James Goodfellow earn for inventing the PIN? £10 — roughly £160 in today's money — paid as an employee bonus because the patent was assigned to his employer, Smiths Industries. He earned no royalties.

Is James Goodfellow in the Scottish Engineering Hall of Fame? Yes — he was inducted on 7 October 2016, alongside earlier honourees including James Clerk Maxwell, Alexander Graham Bell and John Logie Baird.