During the evidence session, the Department failed to provide a specific answer to questions about the characteristics of the illegal population or the evidence it used to make decisions.22 We asked the Department to provide us with facts to support its claims rather than possibilities or speculation.23 For example, the NAO reported that the Department could not support its assertion that a larger number of minor disruptions could have a more lasting effect on organised crime groups than major disruptions. The Department 16 Q 78; C&AG’s Report, para 3.15 17 Qq 34, 42 18 C&AG’s Report, para 2.6 19 Q 77 20 Qq 47, 49 21 Qq 41, 42 22 Qq 34, 36, 80, 95, 97, 105 23 Q 40, 98 12 Immigration enforcement had agreed the NAO report and so it was somewhat surprising to hear the Department respond that it “did not express itself [to the NAO] as well as it could have done” on this point.24 The NAO also reported other cases where the Department could not provide solid evidence for its actions.25 We asked whether acting without adequate evidence left the Department open to the charge that it acted on prejudice. The Department responded that it was determined to act on evidence and data. It admitted its frustration at not being able to have a clearer assessment of its value for money and prioritisation decisions and expressed its wish to improve.26 Challenging assumptions within Immigration Enforcement