Postcode Map. The postcode map shows the location and boundary line for E14, with the map marker a central point of reference for this postcode, marking the central latitude (51.5) and longitude (-0.01) geographic coordinates for satnav purposes.ostcode Map. The postcode map shows the location and boundary line for E14, with the map marker a central point of reference for this postcode, marking the central latitude (51.5) and longitude (-0.01) geographic coordinates for satnav purposes.