The world's first <a href="https://en.wikipedia.org/wiki/Emergency_telephone_number" id="mw6Q" rel="mw:WikiLink" title="Emergency telephone number">emergency telephone number</a>, <a href="https://en.wikipedia.org/wiki/999_(emergency_telephone_number)" id="mw6g" rel="mw:WikiLink" title="999 (emergency telephone number)">999</a>, is introduced in London.