"Stone" is the silliest weight measure ever invented.
Losing a pound or two has to be listed by the poor souls in the UK as losing .14 or .28 stone...not very easy to work with while dieting.
Maybe more useful for weighing horses and cattle
(Height measured in "hands" and "feet" is also weird.)
If EVERYONE switched to metric the world would be a saner place to live.
The United States under Jimmy Carter was geared to go metric, but Ronald Reagan apparently couldn't deal with the change (Alzheimer's, remember) and the U.S. was forced back to inches, feet, yards, pounds, miles, hectares, rods, acres and what have you.