Gloria joins the cobbles in tonight's (September 5) episode as she pays a visit to her daughter Stella. She has been tipped to stir up life in Weatherfield in the coming weeks with some outspoken remarks and a controversial attempt to turn the Rovers Return into a B&B.
In a new Daybreak interview broadcast today, Johnston commented: "Gloria, what can I say? She's a bit of a one-off. I don't know what people are going to make of her - she's not of the norm!
"She doesn't take prisoners really, she makes enemies, she's outspoken, a very selfish woman I think. But I have to find all the good things about her, otherwise I couldn't play her!"
The Royle Family star also revealed that she would like to secure a US movie role in the future.
Johnston explained: "I really miss belonging, I think, so that's what's really nice about [Coronation Street]. I've always said I'd love to do a big Hollywood movie, even if it was only a little bit-part, just to have the experience of how the whole thing operates - not to be a massive star, but just to see how the cogs work. It's like the big end of everything."
However, she added: "I feel very good about where I am. I've got my grandson and my goddaughter - I'm an honorary grandmother to her baby. I'm seeing them all this weekend. So my life is very rich and I do feel privileged that it is so rich because I know that not everyone is so fortunate."
Coronation Street airs Gloria's first scenes tonight at 7.30pm on ITV1.