The 'Burn' hitmaker, who is dating McBusted bassist Dougie Poynter, has been good friends with the superstar DJ for a number of years but witnesses claim they appeared closer than usual at London's Mahiki nightclub on Saturday (21.06.14) after Capital FM's Summertime Ball at Wembley Stadium.
A source told The Sun newspaper: ''Calvin and Ellie have been friends for a while but they appeared more than that this time around.
''They were seen holding hands and hugging at the club and more than a little bit all over one another.''
Calvin, 30, and Ellie, 27, have been back in the recording studio recently after their song 'I Need Your Love' became a hit last year and they were filmed kissing in the video for the track.
Ellie uploaded a number of photographs of the pair working on new material on her Instagram account and fans were quick to point out how great they look together.
Meanwhile, Calvin has just split from 'I Will Never Let You Down' hitmaker Rita Ora, who was also seen with a mystery man on Saturday night at London's trendy new nightspot Chiltern Firehouse.
Calvin reportedly ended his year-long relationship with Rita, 23, by announcing their split on Twitter and the singer was left ''embarrassed'' by the shock announcement.
There are currently five separate teams working on 'Game of Thrones' projects at HBO.
She's a big fan of the band and this week she got to perform with them.