A18.—(1) Subject to paragraph (2), every regular policeman—
(a)who is not a member of the metropolitan police or an overseas policeman shall be required to retire—
(i)if he is the commissioner or assistant commissioner of police for the City of London or is a chief constable, deputy chief constable or assistant chief constable, on attaining the age of 65 years,
(ii)if he is a superintendent or inspector, on attaining the age of 60 years,
(iii)if he is a sergeant or constable, on attaining the age of 55 years;
(b)who is a member of the metropolitan police shall be required to retire—
(i)if he is an assistant commissioner, on attaining the age of 60 years,
(ii)if he is a deputy assistant commissioner or commander, on attaining the age of 57 years,
(iii)if he holds any lower rank, on attaining the age of 55 years.
(2) The time at which, under paragraph (1), a person shall be required to retire may be postponed, if the person concerned holds a rank above that of superintendent, by the police authority, and, if he holds the rank of superintendent or any lower rank, by the chief officer of police:
Provided that no such postponement or postponements shall extend beyond 5 years from the time at which, under paragraph (1), he would have been required to retire.
(3) Paragraph (1) has effect subject to paragraphs 5(2) and 6(3) of Part VII of Schedule J.