Ariana Grande Parties It Up With Niall Horan In London<br /><br />What fun! Following her sold out concert in London, Ariana Grande was spotted partying with Niall Horan and her ex Nathan Sykes. <br /><br />Prior to meeting up with Ariana and Nathan at the club, Nial was actually in attendance at her big show! Later in the night, Ariana posted a hilarious video to Instagram showing Nial and herself sucking in helium from lilac colored balloons.
