(29) Every member of a police force maintained for a police area and every special constable appointed for a police area shall, on appointment, be attested as a constable by making a declaration in the form set out in Schedule 4—
(a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(b) . . . before a justice of the peace having jurisdiction within the police area.