The Two Pints of Lager and a Packet of Crisps star has taken on the role of Charmian Brent, the wife to notorious train robber Ronnie Biggs (Danny Mays).
The ITV1 show Mrs Biggs will air as a five-part drama, which will start from the couple's first meeting on a train in 1957 through to the date of the train robbery in 1963.
It will also feature details of the couple's lives on the run in Australia, as well as Biggs flying to Rio with the police closely on their tales.
When Biggs fled for Brazil, he left Brent and his three sons in Australia. While he was away, he fathered a child with another woman.
Smith said that she formed very close bonds with all of the children who were in the series and that she still keeps in contact with them now.
She said: "They all write me cards now. On my birthday I got lots of Mum cards."
Sheridan also spoke about the advice she got from the real Charmian Brent about her role, adding: "I've never been broody but after this I am!
"Charmian was an incredible mother and I only have dogs."
Mrs Biggs will air on ITV1 in the autumn.
