Spotlight conversion in UK units

If I type 1 pint & # 39; in Spotlight, I'm told this equals 0.47l. This is true for US units, but I'm in the UK, where a pint is 0.57 liter. Many other imperial units, such as the gallon, are different in the UK, so the problem is not unique to pints.

I often do quick conversions using Spotlight for cooking and brewing, but I only recently realized that the system is set to use measurements in US units.

As far as I know, all my locales are set to the UK, but I must have forgotten something somewhere. How to tell Spotlight to use British measures?