Bradshaw-White told TV Times: "I'd never wanted to do EastEnders. I always thought, 'God no, I can't cope with that sort of fame'. But all of a sudden I got older and felt more chilled out.
"The casting director said she had me in as her wild card for Shirley's sister. The character was originally supposed to be an overweight 50-year-old who's past it. I turned up looking lovely to ask them if they had anything else, and they rewrote it for me."
She added: "It's such a good part. Tina is really funny and has some brilliant one-liners. She and Shirley spend a lot of time shouting, but there's real love there. They don't shout through anger, it's just what they do, and the next minute they're talking normally or giggling."
Bradshaw-White's previous screen credits include roles in This Life and Holby City.
Digital Spy Soap Scoop video - press play below to watch Amie Parker-Williams reveal gossip on Jai's secret being exposed in Emmerdale, Kat and Alfie edging closer to a reunion in EastEnders, and bullying stories on the way in Coronation Street and Hollyoaks.