As I understand it, there is no mandatory retirement age for ATCOs in the UK, thanks to the EU Age Discrimination legislation which came into force late last year. So long as you have a valid CAA Medical Cert., you can carry on working as an ATCO. Competence and the ability to survive night shifts may be another matter... I know of one UK ATCO who was still working as a valid ATCO well into his late 60s. The age at which you are deemed to have reach Pension entitlement varies with employers.