Call for maps.google.co.uk inside your browser

Put into the search row next to the google-logo your destination (here: Downing Street in London)

Google will mark the found location.

Click with your right mouse-button on the found location

A window pops up with a submenu

Click 'What's here'

Now in that searchrow, where you just had put in your location Downing Street, will now appear latitude and longitude, your coordinates

The first figure before the comma is your latitude, the second the longitude.

Put in the coordinates following this format [latitude,longitude] into the searchrow of Google. Using the coordinates in this example Trafalgar Square has been found.

Watch out for the slight variation against the coordinates for Downing Street.