Alan Turing is to feature on the UK's new 50-pound ($63) note. Among many other achievements, the mathematician and wartime code-breaker proposed a test to determine if a machine can be described as intelligent. The smartest course-of-action might be to scrap high-denomination banknotes rather than renewing them, but the Bank of England's revamp of its highest-value bill in public circulation just about passes its own Turing test.

True, cash usage is declining and there are few everyday uses for fifties. They rarely appear in most Brits' wallets and, as with the American $100 bill or higher-value euro notes, economists worry that the biggest denominations are mainly useful for money launderers, tax evaders, drug lords and the like.

Yet with 50-pound notes, that logic is marginal. They account for only a quarter of the value of paper money in circulation, compared with just under half for 500-, 200- and 100-euro ($562, $225, $112) notes combined, over 80 percent for US $100 bills, and a whopping 93 percent for Swiss notes worth 100 francs ($102) or more, the largest of which carry a truly private bank-worthy 1,000-franc value.

As a percentage of the UK economy, the value of outstanding 50-pound notes is correspondingly tiny when set against that of high-value notes in Japan, the US or Switzerland. That suggests the case for getting rid of Britain's highest-denomination note is weaker than for equivalents elsewhere.

Also, people and businesses aren't yet ready to go digital. The independent Access to Cash Review said in a March report that as many as 8 million people in the UK still depend on hard cash. That calls for maintaining the existing cash infrastructure while ensuring the progressive shift to digital payments is as inclusive as possible.

Partly swayed by such considerations, the UK's Treasury said in May that cash is here to stay, including the 50-pound note and, at the other end of the scale, the penny coin. The refreshed note will at least be harder to counterfeit than the old one. For anyone undecided, it's also a chance to give Turing - a genius recognized during his lifetime but nevertheless hounded for his homosexuality - the public pedestal he deserves.

The author is Richard Beales, a Reuters Breakingviews columnist. The article was first published on Reuters Breakingviews. bizopinion@globaltimes.com.cn