1.00pm: Digital Spy is right up in the front row for this panel - exciting! For the next hour, feel free to chip in with your own thoughts using the Facebook comment feature below!
1.13pm: A video recap of the past three series elicits huge whoops and cheers from the crowd. The moderator then introduces a trailer for series four - aaaaah! The darkest hour is just before the dawn...
1.17pm: The surprise guest is introduced - Santiago Cabrera (Lancelot). Next up, Katie McGrath (Morgana), Bradley James (Arthur), Colin Morgan (Merlin) and Anthony Head (Uther), plus exec producers Johnny Capps and Julian Murphy.
1.18pm: The big announcement - Merlin has been recommissioned. Series five is a go!
1.19pm: Johnny Capps explains that having two series ahead gives them "creative space" to focus on their characters and "slow-burning" story arcs.
1.20pm: What's happening next series? Morgana will return, and her magic is just as strong as Merlin's! "Finally!" gasps Katie McGrath.
1.21pm: Colin Morgan promises that there a lot more surprises to come, and adds that the series will grow more "mature" this year. He explains that Merlin's story arc will see him finding his true place in the court of Camelot.
1.22pm: Katie explains that it's "much more fun" to play the evil Morgana. She calls her character "a ticking time-bomb" and insists that she will definitely explode in series four!
1.24pm: Bradley claims that his own character's purpose is to "have a sword, and play around with it" – even this mild innuendo excites the rabid Merlin fans! "When Johnny and Julian found me, they were looking for a guy who could get physical," says Bradley. He's not helping cool down the fanboys and girls.
1.26pm: Santiago Cabrera promises that the knights will be a strong unit in series four. "Arthur and Lancelot get their swords out a lot," quips Bradley. Santiago also promises a bit of flirtation between Lancelot and Gwen (Angel Coulby) in future episodes. The exec also promise "an unexpected twist" to the Arthur / Gwen / Lancelot love triangle.
1.28pm: Angel Coulby makes an apperance via a pre-recorded video message, and introduces new cast member Nathaniel Parker (Arthur's uncle Agravaine).
1.29pm: Why do the exec producers do so many "terrible things" to Uther? Anthony Head explains that Uther has had to face up too his past actions, and the repercussions will continue in series four.
1.32pm: Anthony Head insists that Uther will never give up his crown to Arthur, but admits that a "battle for power" will occur between the father and son.
1.33pm: The cast nominate their favourite moments from the series. Santiago is excited about a moment coming up for Lancelot in series four - he gets to meet the dragon! Katie picks "the first time that Morgana got to blast a guy against a wall!"
1.34pm: Bradley's choice? The scene in which Arthur's knights assemble around the round-table. "it was a shiver-down-the-spine moment," he explains. Colin picks the dragon attack on Camelot from the series two finale, while Anthony admits he's torn between the Arthur / Uther sword battle...and kissing a troll!
1.37pm: Next up, a video blooper reel from the new series! Highlights include Bradley being unable to control his horse, Nathaniel Parker giggling incessantly and Colin doing a cartwheel.
1.41pm: Katie promises that the fourth series will be "more filmic", while Johnny Capps reveals that series four will feature more "epic, vast, magical landscapes" with more green-screen shooting.
1.42pm: Any chance of a romance for Merlin or Morgana? "Merlin's never been lucky in love," says Colin. "Notoriously, in legend, he hasn't had any luck with girls. I think it'd be interesting to see him happy in that respect, but he's got a lot on his plane at that moment!" Katie McGrath requests a good-looking suitor for Morgana. "We'll find you a troll," jokes Johnny.
1.44pm: It's fan question time! The first audience member reveals that it's her birthday, and Bradley James leads the audience in rendition of 'Happy Birthday'. The fan's question - are filming kissing scenes awkward for Bradley and Angel? "It doesn't feel that much like a romantic moment," says Bradley. "It's not awkward, because it's just very mechanical. But I'm glad it's coming across that we've got some chemistry!"
1.46pm: The next fan asks if we'll see Merlin "kick some tail" this series. "Two words - you're gonna," says Colin.
1.48pm: Katie is asked if she puts any aspects of her own personality into Morgana. "She's more the woman I want to be," replies Katie. "She's confident, she's self-assured - who wouldn't want to be like that? Plus, everybody loves a bad girl."
1.50pm: Do any "shenanigans" occur on-set? All eyes turn to Bradley James, who admits that he pulls the "occasional practical joke", but insists that Colin and the knight also join in with the pranks.
1.51pm: A fan dressed as Pokemon's Ash Ketchum asks what type of scenes the cast prefer filming. Anthony Head's answer somehow diverts into discussing cast members with cloaks attempting to use the toilet on-set. "The variety that you're given within your role is vast," suggests an on-topic Bradley. "It's what makes it interesting and entertaining for us to do."
1.53pm: Someone asks the big question - when will Arthur discover Merlin's magical secret? "To reveal it to someone who, at this stage, cannot possibly comprehend who he is and what he stands for, would ruin everything," explains Colin. Julian Murphy also hints that Merlin will have a new reason to keep his magic secret in series four.
1.55pm: Last fan question - what would Uther have done if he'd learnt about Morgana's magic while she was still on the side of good? "He'd have probably set her on fire or thrown her in a dungeon," suggests Anthony Head. "Can you blame her for how I've turned out?" asks Katie.
1.57pm: One more look at the fantastic series four trailer - featuring plenty of action with the knights, some Arthur / Gwen smooching, another appearance from the aged Merlin and... Arthur with the king's crown?? - and that's a wrap! Hope you enjoyed this Merlin panel live-blog, direct from San Diego!