On almost all days the sun does not reach its highest point (solar noon) exactly at 12 noon. Have a look at the graph on this site (The red line is the time of

On almost all days the sun does not reach its highest point (solar noon) exactly at 12 noon. Have a look at the graph on this site (The red line is the time of solar noon): https://www.timeanddate.com/sun/uk/greenwich-city https://www.timeanddate.com/sun/uk/greenwich-city Even in Greenwich, 12 noon winter time can be off of solar noon by about 15 minutes in either direction throughout the year.