From what I understand about UTM Northing and Easting values..
In the Northern Hemisphere, Northing is the number of metres from the equator.
Easting is based on the Central Meridian (CM) of the zone having a value of 500,000 thus anything East of the CM would be 500,000 PLUS the number of metres from the CM and anything West of the CM would be 500,000 MINUS the number of metres from the CM
My confusion arises from a Northing and Easting which is in the UK, for example: Northing 172405 Easting 471267
I know that this location is 51°26′46″N , 000°58′33″W (Not very far West of London)
In this example, clearly London is way more than 172km from the equator..
So the Northing of 172495 must be measured from some other point.
Where is it actually measured from?