DistanceTo

Easting/ Northing

EastingNorthing from = new(318768, 175746);
EastingNorthing to = new(326956, 180146);

double result = from.DistanceTo(to);

Latitude/ Longitude

LatitudeLongitude from = new(51.474821, -3.1710057);
LatitudeLongitude to = new(51.515495, -3.0540461);

double result = from.DistanceTo(to);