The 'RIP' singer joined the X Factor winner and his fellow finalists after the latest leg of the show's tour, while she had just performed in the city for her 'Radioactive' tour.
Ora stayed with Arthur for most of the night at the post-show party, according to The Mirror.
Although the pair left the venue separately, Arthur was apparently seen leaving Ora's hotel the following morning.
Arthur has been romantically linked with the singer previously, with a source telling The Sun: "James is a big fan of Rita. He has already exchanged a few texts with her and is hoping it might lead to something more.
"They've been flirting a bit and having a laugh. But it's still very early days."
Ora appeared as a guest judge on The X Factor last year, and gave Arthur her seal of approval before he won the competition.
The 'Shine Ya Light' singer recently revealed that she turned down a permanent slot as a judge on the show for 2013.
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