The ‘radioactive cheque’ was a machine-readable key.
Tiny traces of carbon-14 identified the voucher so the machine could match it to a four-digit PIN. The paper carried the proof, and the machine consumed it after paying out.
That is the delicious tension inside the first cash machine: cash became available after hours before a machine could see your account. The cash was automatic; the relationship was still paper.
See Historic England’s listed bank →Barclays chose a building that made a good laboratory.
Help before ‘not bad enough’ becomes a crisis.
Rainbow Rogues’ Access Without Barriers Fund in Scotland backs inclusive family support without a diagnosis and open-access community counselling without statutory thresholds or long waits. Its live page shows £45 donated plus £6.25 Gift Aid toward £2,070; £69 funds one counselling session.
Support early, open-access help →The PIN patent came before the cash machine.
Thursday: how Paisley engineer James Goodfellow filed a card-and-secret-number patent in May 1966—13 months before Enfield’s opening—and why invention credit still gets tangled.