Emily Watson has described how playing a bereaved mother in a drama based on the London terror attacks was one of the toughest roles she has ever taken on.

The Angela’s Ashes star plays Julie Nicholson in A Song For Jenny, whose 24-year-old daughter Jenny was killed in one of the tube bombings on July 7, 2005.

A Song For Jenny
Emily Watson plays Julie in A Song For Jenny (BBC)

She said: “Having to inhabit the deep traumatic grief and shock was pretty hard.

“To contemplate what happened to Julie’s daughter happening to my own, is a brink that I have to pull back from. In rehearsals, it was as if we had to stop ourselves from letting everything flow because it was too much, and we had to hold it back and wait for the camera to be there because it was so devastating.

“Enjoy is not really the word – but there was a great sense of serious commitment among the cast and crew. Unlike anything I’ve experienced.”

Nicola Wren plays Jenny in A Song For Jenny
Nicola Wren plays Jenny in A Song For Jenny (BBC)

Emily, who has two children, was pregnant with her first at the time of the attacks and Julie, who she plays, said that it was vital to her that whoever played her should have children of their own.

Julie explained: “I believed it was important that whoever played me should be a mother, and understand viscerally the powerful bond.

“Emily is an extraordinary and courageous actor who takes risks. Her stillness and quietness is as powerful as her actions and spoken words. There were times when I didn’t know if I was watching Emily or myself.”

A Song For Jenny airs on BBC One on Sunday, July 5