An Islamist explosives expert now in a Northern Ireland prison conducted dummy runs for terror attacks at Dublin and Knock ************************************ A convicted al-Qaeda bomb-maker serving a jail sentence in Northern Ireland carried out dummy runs for a potential terrorist plot at Dublin and Knock airports, The Observer can reveal.Last Tuesday the expelled Islamist cleric Omar Bakri Mohammed was seen exhorting young British Muslims in an online broadcast from Beirut to target Dublin because he incorrectly believed US troops used the airport as a transit centre on the way to Iraq and Afghanistan. Now it has emerged that key al-Qaeda...