The difficult task facing national court judges in assessing the proportionality of mandatory retirement measures in age discrimination cases should not be underestimated. Such assessments often require judges to immerse themselves in history, science, economics, sociology and even psychology in answering this difficult question. The lack of guidance from the European Union level adds to the complexity of this task. This article provides a guiding model for the assessment of such cases at a national level which involves an analysis of four specific factors: the specific economic sector, the availability of a pension, the impact of the mandatory retirement measure on the right to work and earn a livelihood and the importance of consent to the measure. The article also addresses what appears to be a fifth factor in the case law of the courts of England and Wales: the particular age chosen, although the necessity and current interpretation of this factor is challenged. The article provides a foundational model for future cases involving mandatory retirement measures which will assist in reducing fragmentation and inconsistency of decision making, provide more certainty and clarity for both claimants and respondents as to the legality of such provisions and reduce the potential for the inevitable undermining of the age discrimination rules which currently exists.