Loads of Walter White's lines in Breaking Bad became instant fodder for t-shirts, mugs and posters picked up during freshers' week fairs.

However, Bryan Cranston says that his favourite line from the series is slightly more off-piste than, "I am the one who knocks," "I did it for me," or "I am not in danger - I am the danger".

Cranston told Entertainment Weekly that it's a line from 'Blood Money' in the final season of the show: "Tread lightly".

"First of all, it’s only two words so I go through it quickly," he said. "So, there. I confess. There is an expediency to it — and economy. I enjoy brevity." Cranston said that it is the phrase which he reaches for most often while autographing fans' bits and pieces, which makes those encounters sound both cosmic and a slightly ominous."

He went on: "It’s his credo. In many ways, he was very careful. Even though he stepped into landmines, he was very careful almost all the time."

It was when he strayed from his self-imposed limits that White gets into the hottest water: "When he didn’t follow that credo is when he found himself in the most troubling condition."

We might not have seen the last of White and his pal Jesse Pinkman yet either. Last week, co-creator Vince Gilligan revealed just how desperately he wants to work a cameo from the pair into the spin-off Better Call Saul.