The move to decimalisation in the UK started 200 years ago, in 1821 when a Parliamentary Committee was set up, although it eventually rejected the proposals. Various attempts were made to change the currency, but it was a report published in 1963 that set the stage for the UK to change its currency at last.

The plans for decimalisation would see the pound retained, as it was a global reserve currency at the time, but the shilling was to be abolished, and the pound subdivided into 100 "new pence" - each worth 2.4 old pence.

The penny was nearly called the cent, but that was dropped as it sounded too foreign to British consumers. It did mean the oddity of having old pence (d) being replaced with new pence (p).

Although there was a fixed deadline of 15th February 1971 for Decimal Day, in fact, the two currencies ran alongside each other for a couple of years. The new 5p and 10p coins were introduced in April 1968 to replace the shilling and florin coins, followed by the 50p coin in October 1969, replacing the 10 shilling banknote.

For many years, the 5p and 10p coins circulated with New Pence written on them, which doesn't happen any more.

For a couple of years, shops showed two prices, in old currency and the new decimal currency to help people get used to the new system before it became mandatory.

To help, if that's the right phrase, Max Bygraves released a song promoting decimalisation, which inexplicably was not a success in the pop music charts. Meanwhile, the government started its own massive education campaign with posters, booklets, and films.

Naturally, London Underground had to prepare as well for what it described in its staff magazine as "the massive problems the changeover will raise".

A number of articles appeared in the staff magazines in the two years leading up to the currency swap, explaining how it was all going to work. The changeover wasn't just a case of training staff across the entire of the London Transport network but also upgrading all the coin counting and ticket machines in the tube stations, and the handheld ticket machines used on buses. As with the shops, the tickets also had to be dual-currency for a couple of years, so they all needed to be changed - twice.

As reported in the London Transport Magazine, there were also worries about the new 50p coin, as although it was designed to work with coin counting machines, it later turned out that none of the existing coin-counting machines could in fact handle it.

In addition, once a coin acceptor unit was developed to fit into their ticket existing machines, they then needed to be fitted to the machines - a laborious manual process for every single machine in London Transport. The works were carried out by London Transport's ticket machine works based in Brixton. This was also where some 10,000 Gibson bus ticket machines were refitted to issue tickets in the new currency.

It cost £80,000 to convert the coin machines on the London Underground to decimal.

There was also the staff training to consider so that they weren't as confused as customers during the transition. A number of training centres were set up in offices around London, and even mobile training centres in ten specially converted Routemaster buses.

During the final six months leading to D-Day, 22,000 cash handling staff at London Transport attended catch-up training classes.

In the few remaining months to the switchover, 750,000 posters were printed to warn people who might somehow still be unaware that all their money was changing, that it was about to do so. Also, 1,500,000 leaflets were sent to schools to educate schoolchildren about the new fares and coinage.

To read the complete article, see:
50 years since London Underground switched to decimal currency(https://www.ianvisits.co.uk/blog/2021/02/09/50-years-since-london-underground-switched-to-decimal-currency/)