No workman employed in any industry who has been in continuous service for not less than one year under an employer shall be retrenched by that employer until -
(a) the workman has been given one months notice in writing indicating the reasons for retrenchment and the period o notice has expired, or the workman has been paid in lieu of such notice, wages for the period of the notice;
(b) the workman has been paid, at the time of retrenchment, compensation which shall be equivalent to fifteen days average pay [for every completed year of continuous service] or any part thereof in excess of six months; and
(c) notice in prescribed manner is served on the appropriate Government [ or such authority as may be specified by the appropriate Government by notification in the Official Gazette].