, Britain
The banks shut on the afternoon of Wednesday 10 February 1971 and did not open again until the Monday. For a shopkeeper that was four evenings, and the job was not banking. It was going along the shelves with a pencil and a conversion table, working out what a tin priced at one shilling and threepence was going to be called on Monday morning.
Decimal Day was 15 February 1971. It had been announced in 1966, prepared for years, and it still arrived as a week of physical work for every business in the country that sold anything to anybody.
The old money had two divisions and both of them mattered
Before decimalisation a pound was 20 shillings and a shilling was 12 pence, which made 240 pence to the pound. That sounds merely awkward. In practice it was rather good for retail, because 12 divides by 2, 3, 4 and 6, so a shilling split cleanly four ways and three ways in a way that 10 does not. Selling three of something for a shilling was fourpence each, exactly.
The new system had 100 new pence to the pound. One shilling became exactly 5p, which was the easy case, and the reason the 5p and 10p coins had already been in circulation since 1968 at the same sizes as the shilling and the florin. The 50p arrived in October 1969 and took the ten shilling note out of the system before the main event.
The hard case was the old penny. One old penny was five twelfths of a new penny, which is not a price. Sixpence became two and a half new pence, which is why the sixpence stayed legal tender as 2½p for years afterwards. The halfpenny, the penny and the threepenny bit lost their status on 31 August 1971.
Anything cheap was therefore unconvertible without a decision, and the decision was yours.
The repricing was the work, and the rounding was the argument
A shop with 2,000 lines had 2,000 of those decisions, and the guidance said round to the nearest new penny. Half of your lines rounded down and half rounded up, in theory.
In practice a business rounding down on a fast selling low margin line and up on a slow one was not being dishonest, it was surviving, and the customer standing at the counter saw only the ones that went up. The Decimal Currency Board published conversion tables, retailers printed them on cards for the counter, and the argument happened anyway. Every shopkeeper in Britain spent 1971 explaining that a shilling was five pence and being told it never used to cost that.
There was a second cost nobody talks about. Everything mechanical that handled money had to change: tills, weighing scales with price computation, vending machines, ticket machines, meters, telephone boxes. A small business either bought a new till or ran a converted one, and the trades that made a great deal of money out of 1971 were the ones servicing coin-operated equipment.
Books were the third job. A trading year that straddled 15 February 1971 had two currencies in it, and the ledgers, the invoices in the file and the outstanding debts from December all had to be reconciled into one set of accounts. For a small firm without a bookkeeper, that took the summer.
The changeover went faster than the plan allowed for
The official plan permitted a long transition, with dual pricing and both currencies circulating while the country got used to it. It turned out not to be needed. Within weeks most shops had gone over entirely, because running two prices on everything was more trouble than the conversion had been.
What lasted was the vocabulary. People counted in shillings for years, talked about "two bob" well into the 1980s, and mentally converted prices back into old money to judge whether something was dear. A generation did their thinking in one currency and their paying in another, which is a strange thing to have to price against.
The belief that it caused inflation outlived the evidence
Ask anyone who was trading in 1971 and a fair number will tell you decimalisation put prices up. The belief was widespread at the time and it has survived for fifty years.
The timing did not help. Inflation was already high in 1971 and got dramatically worse over the following four years, for reasons that had far more to do with oil, wages and the collapse of the Bretton Woods system than with the shape of a coin. But the visible event was the coin, and the visible rounding was the shopkeeper's pencil, and so the shopkeeper got the blame.
That is worth holding on to, because it is the recurring lesson of every one of these episodes. What a small business is actually judged on is rarely the thing that caused the problem. It is whichever part of the problem the customer can see you doing.
Where this shows up in the game
A Business Baron career can start as early as 1930, and one that reaches February 1971 trades in pounds, shillings and pence until Decimal Day and then converts. The repricing is a real month of work with a real cost, the rounding choice is yours to make across your price list, and customers notice for longer than you would like. It is the clearest example we have of a rule change that generates no revenue for anybody and still has to be paid for by every firm in the country.