Warning: contains moderate Breaking Bad spoilers; don't read on if you aren't up to speed with the latest episode

In one of the busiest sessions of this year's Edinburgh TV festival, Breaking Bad showrunner Vince Gilligan was interviewed by the Guardian's Charlie Brooker on stage, with Laura Fraser, who plays Lydia in the final season, part of an enthusiastic audience. Gilligan is notoriously tight-lipped on spoilers and gave nothing away about how Walter White's journey will end, nor did he reveal much more about the mooted Saul Goodman spin-off, other than to say, "Knock on wood, I have a good feeling about it." Gilligan did, however, reveal a number of BB anecdotes that were tastier than a Los Pollos Hermanos bargain bucket.

1. Jane's story could have been even darker

Brooker showed the clip of Walt watching Jesse's girlfriend Jane choke to death in season two, explaining that it was the point at which he lost all sympathy for the lead character. Gilligan elaborated that it was the only time the network got in touch to express concern about the show's content. "That was the moment AMC and Sony called me up and said, this one makes us nervous. We had a big phone discussion about it." He went on to reveal that his original idea for the storyline had Walt administering a second dose of heroin: "he kills her on purpose". But this version never made it to the script stage - Gilligan was voted down by his writers. "It's that old story, if enough people tell you you're drunk, you need to sit down. I trust my six writers very much. They told me I was drunk at that point."

2. Mike was a hasty add-on

Jane's death was supposed to be covered up by Saul Goodman, but actor Bob Odenkirk was unavailable to film those scenes due to prior commitments: "So very quickly we came up with the character of Mike the cleaner. It was one of those happy accidents."

3. Breaking Bad looks the way it does because TVs are bigger now

The show's distinctive style is inspired by, among others, Sergio Leone, westerns and Akira Kurosawa, but there's a more prosaic reason that it looks the way it does, with those gorgeous wide shots of Albuquerque. "I realised we had the facility to do that with these big TVs we watch now, as opposed to the little tube TVs we had years ago," he said.

4. Hank was 'an asshole jock' until the writers got to know Dean Norris

Gilligan discussed how much Hank has changed since the early episodes. "[Hank] was by design everything that Walt was not, kind of an asshole jock. Once I got to know Dean Norris, I started to realise how complex he is, and some of those facets made their way into the character. He became less of a jerk and more of a well-rounded character."

5. Vince Gilligan is Walter White

Gilligan started to work on the idea for the show after a two-year period of unemployment. "Breaking Bad came out of some issues I was having at the time," he said. "Walter White and I, unfortunately for me, share a lot of similarities. Pre-meth-cooking," he clarified. "Not Heisenberg." But Gilligan is not very good at science. "I never actually took a chemistry course in my life," he said.