The 31-year-old plays the EastEnders matriarch in BBC One’s drama about her – Babs.
But the daughter of star Ray Winstone found it daunting to play a young Barbara.
Babs starts with her first stage appearance aged six and recalls her turbulent relationship with her father and rocky marriage to first husband Ronnie Knight.
The 79-year-old actress watched the biopic being filmed.
Jaime said: “It was terrifying. I would look out and she would be there staring.
“But she said, ‘Darling, you’re more me than me’, and that was a huge pat on the back.”
Dame Barbara assured her “this is your role” and told her to “keep it camp” when recreating her first run-in with Kenneth Williams on the Carry On set.
Game Of Thrones actress Samantha Spiro plays Barbara in her 50s. To mark her 80th birthday this summer, the EastEnders star even makes her own cameo appearance.
Barbara starred in the Carry On films before playing Peggy Mitchell in EastEnders from 1994.
• Babs will air on BBC One, May 7 at 8pm.