On 11 November 2020 the UK Government published its groundbreaking National Security and Investment Bill (Bill). The Bill will drastically expand the Government’s powers to scrutinise investment on national security grounds, through a requirement for mandatory notification of transactions in 17 identified sensitive sectors backed by a ‘call-in’ power applying to an extremely wide range of transactions across all sectors of the economy, with no turnover or market share thresholds. The Bill will have a particular impact on energy and infrastructure investors since, once the legislation is in force, many of their transactions with a UK nexus will require advance notification and clearance.