The design of the bank note was unveiled before it is set to be formally issued to the public on June 23, Turing’s birthday. The 50-pound note is the most valuable denomination in circulation but is little used during everyday transactions, especially during the coronavirus pandemic as digital exchanges increasingly replaced the use of cash. The new note, which is laden with high-level security features, completes the bank’s rejig of its stable of paper currencies over the past few years. Turing’s image joins that of Winston Churchill on the five-pound note, novelist Jane Austen on the 10-pound note and artist...