Britain's new anti-terrorism chief Max Hill has warned that the Islamic State terror group is plotting indiscriminate attacks on innocent civilians in UK cities on a scale similar to the one executed by the IRA in 1970s. <br/><br/>The recently appointed Independent Reviewer of Terrorism Legislation said hundreds of British jihadists who are returning from war zones pose a level of threat to the UK not seen since the Irish Republican Army (IRA) bombings 40 years ago. <br/><br/>More than 50 people were killed by IRA attacks in Britain during the 1970s.