Jaime Winstone agreed to play Peggy Mitchell after getting a "sign" from Dame Barbara Windsor.
The 37-year-old star - who will play the iconic 'EastEnders' character in a flashback episode set in 1979 showing the unravelling of the Mitchell family's chequered past - feels like she has the approval of the late actress, who played the character from 1994 until 2016.
Jaime said: "I have such a deep connection with her and respect for her. I did have my own sort of question to her.
"I did actually have a little word with Barbara up above, and I got my signs, and I just felt like it was written for me.
"So I felt like I got the go ahead and Scott [Mitchell, Barbara's husband] approved it and everything."
Jaime - who previously worked with Barbara when she portrayed the actress in BBC drama 'Babs' - revealed the key sign was a butterfly in her garden.
She told Metro.co.uk: "It's quite private, but...it was a butterfly, actually. It was days before I was deciding, and it's an opportunity of a lifetime [but] I still had to think about it.
"It was a little blonde butterfly that kept coming in my garden and I was thinking...we don't normally get too many butterflies.
"So that was my sign, 'that's her'. You know when you know."
Jaime admits she had "a deep chat" with her agent before accepting the job.
Revealing her response when the call came in to play the iconic character, Jaime confessed: "It was scary. I had to think about it properly, I had a deep chat with my agents about it but when it's an opportunity like this - Peggy Mitchell, the landlady of our nation - it's an honour for me."
Jaime has admitted the flashback episode is "turbulent" and "fast paced".
She explained: "It's really about the family before the Mitchells became the Mitchells ... and also see why Phil is who he is.
"It's set in 1979, the backdrop is London, grim, quite skint, there's rubbish on the streets ... and it was different for women then, women knew their place and did the cooking, the cleaning and were very proud home keepers.
"It's a turbulent episode - there's lots to take in. It's fast paced ... you'll see a more vulnerable side to her. It's the making of how Peggy Mitchell became Peggy Mitchell."