Police Authority Police Authority Changes not yet applied. Later legislation changes this provision in ways not yet written into the text below: Pt. 3 functions no longer exercisableexcluded by Railway Policing (Scotland) Act 2017 s. 4 Pt. 3 functions no longer exercisableexcluded by Railway Policing (Scotland) Act 2017 s. 5 18The British Transport Police Authority 19Exercise of functions Police Authority