James Corden was in brutally honest mood this afternoon as he reflected on his least favorite Gavin & Stacey episode at the BBC Comedy Festival . “It’s a very very very bad half hour,” he said of Season 1 Episode 2 of his beloved BBC sitcom. “It’s an awful episode.” So why is Corden so damning? He said he and co-creator Ruth Jones “backed ourselves into a corner” by making Gavin propose to Stacey at the end of Episode 1. “It had this very romantic end, so you can’t do another romantic proposal [in the next one],” he explained. Episode 2 of the first series sees a huge misunderstanding on the phone cause Gavin to have to drive to Wales to resolve his relationship. At that point in their earlier careers, Corden and Jones didn’t realize Gavin & Stacey was “not a sitcom but closer to a comedy drama,” he said. “We were conscious of this half-hour comedy thing and I don’t think we trusted that actually the characters will be the thing that will be funny,” he added.…