Five internationally acclaimed writers consider the impact of the momentous events of September 11th, 2001.
Ten years on, these authors use imaginative letters to reflect on the consequences for Britain, America and the world.
The final 9/11 Letter is by the former Children's Laureate, Michael Morpurgo.
Among the more than one hundred books he has written is 'War Horse', the stage version of which this year won a Tony Award on Broadway, and is being made into a film by Stephen Spielberg.
The imagined writer of Michael Morpurgo's letter is Ginny, who, when the first plane smashed into the North tower was waiting on a bench in Central Park for her husband to return from breakfast with their son, their first meeting since a rift seven years previously.
What happened on 11th September, 2001 rent many families - including Ginny's - asunder, yet it also brought people together.
Michael Morpurgo's letter, which he has titled 'A Proper Family' movingly explores this ambiguity.
Producer: Julian May.
Michael Morpurgo's letter-writer Ginny was waiting in Central Park for her husband and son