Switching to metric didn't mean the end of gallons

You list a “key Brexit success” (UK reports, 7 January) as being able to sell items in pounds and ounces. It is informative to recall when Canada changed to the metric system in 1975. Paint cans changed from a gallon to a 4-litre version. Within months these disappeared to be replaced by containers holding 3.785 litres, the size of a US gallon. The moral: if you wish to trade with an elephant, watch what the elephant is doing. Anthony Walter Coldstream, BC, Canada