4. The following provisions of the Act shall come into force on 22nd September 2008—
(a)section 317 (building regulations: time limit for prosecutions) and
(b)section 321(1) (repeals), so far as it relates to the repeal of section 156(5) and (6) of the Housing Act 1985(1), and the entry relating to those subsections in Schedule 16 to the Act.