Industrial Control Systems play an important role in the monitoring, control, and automation of critical infrastructure such as water, gas, oil, and electricity. Recent years have seen a number of high profile cyber attacks on such infrastructure exemplified by Stuxnet and the Ukrainian Power Grid attacks. This naturally begs the question: how should we manage cyber security risks in such infrastructure on which the day-to-day functioning of our society relies? What are the complexities of managing security in a landscape shaped by the often competing demands of a variety of stakeholders, e.g., managers, control engineers, enterprise IT personnel and field site operators? What are the challenges posed by the convergence of IoT and critical infrastructure through the so-called Industrial Internet of Things? And will frameworks such as the EU NIS directive help mitigate the cyber security risks to critical infrastructure? This talk will discuss insights from a multi-year programme of research investigating these issues and the challenges to addressing them.