Within hours of the photograph being taken, the pair were murdered by an as yet unidentified killer or killers.
Hannah Witheridge, 23, sits on the far left of the picture holding a cocktail, and David Miller, 24, is second from right in a blue T-shirt.
Nine days on no arrests have been made. According to 'The Telegraph,' police now believe that two weapons were used to bludgeon the Britons to death on a Koh Tao beach in the early hours of September 15.
The photograph was provided to 'The Telegraph' by someone they met briefly that evening. It was taken at 9.45pm at a popular Australian-owned sports pub called Choppers on the night before the murder.
Miss Witheridge is wearing the same pink top she was wearing just hours later when she was killed, the newspaper reports.
Opposite sits Mr Miller with his close friend Christopher Ware, in a white T-shirt.
Police initially suggested Mr Ware was a suspect in the murders but he was cleared and allowed to leave Thailand after being ruled out by DNA tests, 'The Telegraph' reports.
''The tattooed man closest to the camera, on the far right, is believed to be a traveller called Tom who the group had met on the island,'' says 'The Telegraph.'
Ms Witheridge and Mr Miller are not thought to have known each other well and they arrived at Choppers in separate groups. Once the football game they were watching had finished, they left separately, CCTV footage shows.
Later their two groups linked up again at the AC Bar near Sairee beach, which according to the newspaper is ''a Thai-run nightclub which is known for drunken brawls and strong cocktails.''
Their bodies were found on the beach with first light next morning.