Joe Duffy's toughest question yet: how many children died in the Rising?

"The two-year-old who died for Ireland" – not so catchy is it? It's not something you'd want to grab your bodhran and squeezebox and write a comeallye about. I wonder was it shame that made the 40 children who died during Easter Week 1916 disappear? They weren't mentioned during the 1966 commemoration, says broadcaster Joe Duffy in his evocative, informative documentary Children of the Revolution (RTÉ One, Sunday), and if they are mentioned in history books it is briefly and often inaccurately, he adds.

Duffy’s three-year research project came about out of curiosity, to respond to what he thought was an obvious and surely already well-answered question: how many children died in the Rising? It turned out no one knew. His research for the book of the same name provided answers and this film, based on the book, looks at the short lives and deaths of some of those 40.

Some were killed by the rebels, some by British snipers, most were innocent bystanders, a few were taking part. Child actors re-enact some scenes (and that works because it is used sparingly as a dramatic device), such as when 12-year Madge Veale was shot by British soldiers as she looked out the back window of her house on Haddington Road. She was wearing a green jumper and the soldiers mistook her for a rebel.

Some of the children's histories tell a wider story, such as the battle of Fumbally Lane: a tiny cottage-lined lane which the Volunteers wanted to take for strategic reasons. The residents – many with sons and brothers off fighting in the trenches in France and many in receipt of the financial lifeline of the Separation Allowance that was given to wives of British soldiers – were incensed and started attacking the rebels. Fifteen-year-old Eleanor Warbrook, whose two brothers had already died in the first World War, hit one of the rebels with a stick and he shot her in the face: you can see why that horrific vignette was airbrushed out of history.

Duffy is a big softie. It's clear how emotionally connected he feels to the stories, how real the children are to him. He creates vivid images as he tells of a two-year-old shot while sitting in his pram, children looting sweets from shops on O'Connell Street, or of mothers battling bureaucracy to get compensation for the deaths of their children. He doesn't have the cool distance we're used to when we've seen professional historians explaining the events of 1916 – though ironically his film is one of the few based on original, new research. The Liveline presenter is filmed at home at his kitchen table, his "Talk to Joe" mug holding down a map of the city spread out on the table, surrounded by books and his research, as if to re-enforce his amateur historian status.

What this film does very well is capture the sense of chaos in the week and the tragedies of the deaths: many of the children's bodies were buried hurriedly in unnamed plots. It is, he points out, remarkable that even now no one can tell precisely how many civilians died in the Rising, although he must get satisfaction by being able to put some number and names on the children. When the book of Children of the Revolution became a best seller at Christmas I was surprised: a book about 40 dead children isn't exactly festive. But this film shows why it worked, by creating vivid stories about the too short lives of as Duffy says "a classroom of children", the previously ignored collateral damage of the Rising.