The actress, whose character Kathy Beale made her return to the soap in Thursday’s hour-long episode, has admitted that she didn’t even tell her kids about her new job.
“Keeping it secret has been awful,” Gillian explains to The Sun. “The only person who knew was my other half Dave.”
Gillian’s secrecy meant her children didn’t even see her scene, as they had no idea she was going to be in the show.
“I was saying to my children the other day, ‘Try and watch ‘EastEnders’, it’s live and Adam Woodyatt (Ian Beale) is going to do something really silly,’” she continues. “I thought that would get them watching it, but my daughter said, ‘I’m working until 9pm’ and my son said he was playing football over the rec.
“So I went, ‘All right, thanks very much’. I even kept it from my sisters and brother, I don’t know how.”
“I had so many missed calls, texts from everybody. Then my son, who is 15, texted saying, ‘99 per cent of the population know — the one per cent, your son, didn’t. But I love you Mum’.
“He asked, ‘If you’re coming back does that mean I can have that moped?’.”
Soap bosses have now confirmed that Kathy’s return wasn’t a one-off, and it probably won’t be long before her character makes her grand arrival in Albert Square.
The shock scene, in which Kathy met Phil Mitchell, stunned ‘EastEnders’ fans on Thursday, and even - almost - managed to eclipse the big ‘Who killed Lucy?’ reveal.
Kathy was last seen on the soap in 2000, and her character was later believed to have been killed off with an off-screen car accident in South Africa.
Find out everything you need to know about the character below...