Foreign firms will find it harder to buy British businesses considered key to national security, as new legislation grants the UK government more powers to vet foreign investment. The National Security and Investment Act, which came into force on Jan. 4, is said to be the biggest shake-up of the UK’s national security regime for 20 years. Under the new rules, the government will be able to scrutinise and intervene in certain acquisitions made by anyone—including businesses and investors—that could harm the UK’s national security. The government will be able to impose certain conditions on an acquisition or, if necessary, block it, though ministers said such interventions will be rare and the vast majority of deals will be able to proceed without delay. Business Secretary Kwasi Kwarteng said, “The UK is world-renowned as an attractive place to invest but we have always been clear that we will not hesitate to step in …