The distance calculated (Method of calculation) from school to child's official residential address - Find a freedom of information request

I would like to know how is the distance calculated (Method of calculation) from school to child's official residential address when offered a place at Spalding High School (Spalding, Lincs) (girls grammar school) and Bourne Grammer School for the last five years, can you provide an example as well please to help understand the distance calculation.

I can confirm that the information requested is held by Lincolnshire County Council. I have detailed below the information that is being released to you.

The distance measurement is found by measuring the distance from the child's home address to the school.

Distances are measured in a straight line and are calculated to three decimal places (for example 1.543 miles) by the Lincolnshire County Council school admissions team, using the 'Synergy' system.

Information about the address used for each application is taken from the Ordnance Survey AddressBase database, which provides 12-figure X and Y coordinates for each individual property. Distances are measured from this point of the child's home to the school.