The 23-year-old singer and the 'Romeo and Juliet' star reportedly hired a section of the pub in London to spend some time alone, reported Daily telegraph.
"They (duo) hired out a section of the pub out of sight, tucked away around the corner. A member of staff was sitting outside stopping customers from going near them," a source said.
"When they did come out they were laughing and joking. They seemed like they were getting on brilliantly - they seemed very close... They were in the pub a few hours," the source added.