Line of Duty is now officially the most watched drama of the 21st century.The hit BBC police procedural aired its series six finale earlier this month which saw record numbers of fans tuning in to discover the identity of H. Latest official figures show that a massive 15.24 million viewers watched the last episode in a week, boosting it ahead of the previous record-holding 2000 episode of Heartbeat which attracted 15.16 million viewers.