It shall be lawful for the universities of Oxford and Cambridge, and for all other bodies corporate and politic, and for all bodies now by law or statute or by any valid usage authorized to administer or receive any oath, solemn affirmation, or affidavit, to make statutes, byelaws, or orders authorizing and directing the substitution of a declaration in lieu of any oath, solemn affirmation, or affidavit now required to be taken or made: Provided always, that such statutes, byelaws, or orders be otherwise duly made and passed according to the charter, laws, or regulations of the particular university, other body corporate and politic, or other body so authorized as aforesaid.