Do you know how many countries us miles instead of kilometers? USA, UK and Zimbabwe. Get a life!
Zimbabwe uses kilometres.
It does however use UK-pattern electricity plugs (while South Africa still uses the older (round pin) UK standard).
One case where the UK standard won out was on time and longitude.
There was an International Meridian Conference in 1884 to agree the world basis for time and longitude measurement, by agreeing the prime meridian.
The railways were instrumental in forcing the adoption of standard time, particularly in the US with its wide spread of longitude and therefore local times.
There were several contenders: London (Greenwich), Paris, Berlin and Washington, although Greenwich was already the de facto standard in many countries.
Greenwich was indeed eventually chosen, mainly because a large fraction of existing navigation charts used longitudes based on Greenwich.
The French wanted a "neutral" meridian that did not cross land - ie somewhere in the middle of the Pacific.
While abstaining on the main vote, the French only adopted the Greenwich meridian in 1911 and even then refused to use the term Greenwich Mean Time.
A further international agreement decided the time system based on GMT should be called Universal Time everywhere.
It's now called UTC - Coordinated Universal Time, which is what you will find it called in international timetables and navigation almanacs worldwide.
We routinely ignore the term UTC and still call it GMT.
The world time authority was not in Greenwich or even in the UK, it was at the Bureau International de l'Heure, in Paris.
This is all regulated today by cooperative international agreements.
The 1884 conference also "hoped" that decimal divisions of time and angular measure would be agreed in the future, to replace the sexagesimal measures.
We do have decimal degrees today (eg GPS readings), but we are still waiting for decimal times of day.