398.This section ensures that the provisions do not result in the same behaviour being criminalised twice. It does this by providing that any byelaws which have the effect of prohibiting or restricting the already prohibited activity in the controlled area cease to have effect (to the extent of the overlap) when the provisions come into force. The section also provides that the powers of the Greater London Authority and Westminster City Council to enact byelaws are limited so as to prevent any dual criminality in relation to any particular activity that is a prohibited activity for the purposes of Part 3. The Greater London Authority has the power to make byelaws under section 385 of the Greater London Authority Act 1999 in order to secure the proper management of Parliament Square Garden. Westminster City Council has the power to make byelaws under section 235 of the Local Government Act 1972 for good rule and government and the suppression of nuisances.