Find the Ordnance Survey grid coordinates (eastings and northings) for the postcode 'MK5 6FE' and display them on a map with a zoom level of 120. Additionally, confirm the primary coordinate system Streetmap.co.uk uses for these grid coordinates.
Navigate to 'streetmap.co.uk'. Use the search bar on the homepage to search for the postcode 'MK5 6FE'. Once the map for 'MK5 6FE' loads, identify the displayed easting and northing coordinates. Navigate to the 'How to link to us' page to understand the format for linking by grid coordinates with a specified zoom level. Construct a direct map URL using the identified easting and northing coordinates for 'MK5 6FE' and a zoom level of 120 (e.g., https://streetmap.co.uk/grid/<easting>_<northing>_120). Navigate to this constructed URL. Confirm the primary coordinate system used by Streetmap.co.uk for its grid coordinates from the 'How to link to us' page or map copyright information.
Successfully navigate to the map for postcode 'MK5 6FE'. Identify the exact easting and northing coordinates for 'MK5 6FE' as 482079 and 236013 respectively. Successfully navigate to a map displaying the coordinates 482079,236013 with a zoom level of 120. State that Streetmap.co.uk primarily uses Ordnance Survey grid coordinates (northings and eastings).