After the EU referendum, the new Prime Minister, Theresa May, promoted him to Minister of State for Security in the Home Office. In December 2017 the Ministerial portfolio was extended to include Economic Crime. He was the Security Minister during the terror attacks of 2017 and the Salisbury attempted assassination of Sergei Skripal. Wallace was appointed to the Privy Council for his role in coordinating the government response to the 2017 Westminster attack.