The Doctor Who star dated the catwalk beauty for 18 months until they parted ways in November (11), but reports suggested they reunited two months later (Jan12).
The couple has now stepped out together for the first time since reconciling, attending the BBC's Hackney Weekend event in the U.K. capital.
They were caught on camera backstage at the festival cuddling, while Smith caressed Lowe's bottom.
A source tells Britain's The Sun, ""Matt was trying to disguise himself by wearing his hood up as he hobnobbed backstage.
""But when Daisy came over he didn't seem to care who was watching. His eyes just lit up and they were locked into deep conversation - hugging each other all the time. At one point he gave her bum a big squeeze.""