In the days after the bloody end of twin French hostage crises on Friday, stories of life-saving courage filter out.

A huge security operation is being prepared ahead of unity marches in France, as the hunt for a fugitive linked to the Paris massacres took a new twist.

A businessman taken hostage by the Charlie Hebdo killers has described how he kept a colleague from their clutches in an act of heroism which helped police capture the fugitives.