Sarah Lancashire said she is "delighted" about the role

Lancashire will play Ms Cannings, who spent two years in prison before her conviction was overturned, opposite Timothy Spall as her husband.

"When I read the script I was very moved. Theirs is a remarkable story," said Lancashire.

Ms Cannings was consulted on the script. Filming begins this autumn.

Ms Cannings was convicted of the murder of seven-week-old Jason in June 1991 and 18-week-old Matthew in November 1999 in April 2002, based purely on the opinion of three experts, including the now-discredited Professor Roy Meadow.

Professor Meadow said there was a 73 million to one chance of two children in the same family dying of cot death.

But no physical evidence was used in the case.

Law change

As a result of her case being overturned, the law was changed so that no-one can be convicted in a criminal case on the testimony of expert witnesses alone, without referring to physical evidence.

Angela Cannings was initially convicted in 2002

Ms Cannings' first child, Gemma, also died of cot death in 1989, but no charges were brought in relation to that death.

The couple have a daughter Jade, aged eight.

"The film is for Jade, my daughter's benefit, so when she is older she can see what it was all about," said Ms Cannings, from Salisbury, Wiltshire.

Lancashire said she found the real-life story remarkable.

"Whilst any parent could relate to the anguish that Terry and Angela must have felt, I cannot comprehend the strength it must have taken to sustain Angela through even a part of a life sentence," said Lancashire.

The drama will be the third collaboration between the BBC's drama and current affairs departments, following Holy Cross and Dirty War.